Uplink transmissions in wireless communications

ABSTRACT

Methods and devices for offloading and/or aggregation of resources to coordinate uplink transmissions when interacting with different schedulers are disclosed herein. A method in a WTRU includes functionality for coordinating with a different scheduler for each eNB associated with the WTRU&#39;s configuration. Disclosed methods include autonomous WTRU grand selection and power scaling, and dynamic prioritization of transmission and power scaling priority.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/115,511 filed Sep. 12, 2017, which is the U.S. National Stage, under35 U.S.C. §371, of International Application No. PCT/US2015/013616 filedJan. 29, 2015, which claims the benefit of U.S. Provisional ApplicationNos. 61/933,169 filed Jan. 29, 2014; 61/955,632 filed Mar. 19, 2014;61/978,630 filed Apr. 11, 2014; 61/989,997 filed May 7, 2014; 62/002,625filed May 23, 2014; 62/007,147 filed Jun. 3, 2014; 62/033,993 filed Aug.6, 2014; 62/060,492 filed Oct. 6, 2014; 62/069,739 filed Oct. 28, 2014and 62/093,965 filed Dec. 18, 2014, the contents of which are herebyincorporated by reference herein.

FIELD OF INVENTION

This application is in the field of wireless communications.

BACKGROUND

Efforts are being deployed to create different means to aggregateresources from different eNBs (e.g. R12 LTE inter-eNB aggregation usingdual connectivity). The objective is typically to enable means for anoperator to offload some traffic from a macro cell/eNB to anothercell/eNB which cell may possibly offer some form of hot spot overlaynetwork, or to enable higher throughput.

A WTRU may be configured for dual connectivity. Dual connectivity may beconfigured by the network either for throughput benefits (mainly for thedownlink) or for offload purposes (relieving an eNB deployed for macrocoverage from user plane traffic towards another eNB deployed forcapacity enhancements). When a WTRU is configured for operation withdual connectivity, it may use radio resources associated to differenteNBs where the interface corresponding to each set of resources isherein referred to as a Uu interface. Each Uu interface may itself beconfigured with one or a plurality of serving cells in case intra-eNBcarrier aggregation is also supported. The WTRU may then be scheduledfor any type of data by a Macro eNB (MeNB) which eNB controls the RRCconnection, as well as by a Secondary eNB (SeNB) which may be used forexchanging user plane data. This form of dual connectivity may also bereferred to as Inter-eNB Carrier Aggregation (inter-eNB CA). In thiscase, the WTRU may be configured with different MAC entities, one foreach configured Uu interface.

Some prioritization and power scaling mechanisms have been specified forintra-eNB CA, however these mechanisms involve minimal if anycoordination between schedulers, and control plane data is onlytransmitted using a single Uu interface.

SUMMARY

Methods and devices for offloading and/or aggregation of resources tocoordinate uplink transmissions when interacting with differentschedulers are disclosed herein. A method in a WTRU includesfunctionality for coordinating with a different scheduler for each eNBassociated with the WTRU's configuration. Disclosed methods includeautonomous WTRU grant selection and power scaling, and dynamicprioritization of transmission and power scaling priority.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A; and,

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A.

FIG. 2 is a system diagram of an example system operating using dualconnectivity.

FIG. 3 is a block diagram illustrating simultaneous transmissions for asynchronized case.

FIG. 4 is a block diagram illustrating simultaneous transmissions for anunsynchronized case.

FIG. 5 is a flowchart illustrating an example application of aprioritization function.

FIG. 6 is a flowchart illustrating an example of dynamic adjustment of aprioritization function.

FIG. 7 is a flowchart illustrating an example application of adaptiveprioritization.

FIG. 8 is a block diagram illustrating an example allocation of power touplink transmissions.

FIG. 9 is a flowchart illustrating another example application ofadaptive prioritization.

FIG. 10 is a flow chart illustrating an example of prioritization bycell group type.

FIG. 11 is a flow chart illustrating an example power configuration foruplink transmissions from a WTRU.

FIG. 12 is a flow chart illustrating an example of power scaling foruplink transmissions.

FIG. 13 is a flow chart illustrating another example of power scalingfor uplink transmissions.

FIG. 14 is a flowchart illustrating another example of power scaling foruplink transmissions.

FIG. 15 is a flowchart illustrating an example allocation of remainingpower on a first-in-time basis to a cell group.

FIG. 16 is a flow chart illustrating determination of a maximum powerfor all uplink transmissions during a time interval for an asynchronouscase.

FIG. 17 is a block diagram illustrating subframes used by the WTRU tocalculate the maximum power for uplink transmissions during a timeinterval.

FIG. 18 is another block diagram illustrating subframes used by the WTRUto calculate the maximum power for uplink transmissions during a timeinterval.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a site controller, an access point (AP),a wireless router, and the like. While the base stations 114 a, 114 bare each depicted as a single element, it will be appreciated that thebase stations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1C may include a mobility managemententity gateway (MME) 142, a serving gateway 144, and a packet datanetwork (PDN) gateway 146. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 142 may be connected to each of the eNode-Bs 140 a, 140 b, 140 cin the RAN 104 via an Si interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the Si interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

3GPP LTE Release 8/9 (LTE R8/9) may support up to 100 Mbps in thedownlink (DL), and 50 Mbps in the uplink (UL) for a 2×2 configuration.The LTE downlink transmission scheme is based on an OFDMA air interface.

For the purpose of flexible deployment, LTE R8/9/10 systems supportscalable transmission bandwidths, which may be one of [1.4, 2.5, 5, 10,15 or 20] MHz.

In LTE R8/9 (also applicable to LTE R10), each radio frame (10 ms)comprises 10 sub-frames of 1 ms each. Each sub-frame comprises 2timeslots of 0.5 ms each. There can be either 7 or 6 OFDM symbols pertimeslot. 7 symbols per timeslot are used with normal cyclic prefixlength, and 6 symbols per timeslot are used with the extended cyclicprefix length. The sub-carrier spacing for the LTE R8/9 system is 15kHz. A reduced sub-carrier spacing mode using 7.5 kHz is also possible.

A resource element (RE) corresponds to one (1) sub-carrier during one(1) OFDM symbol interval. 12 consecutive sub-carriers during a 0.5 mstimeslot constitute one (1) resource block (RB). Therefore, with 7symbols per timeslot, each RB comprises 12*7=84 REs. A DL carriercomprises 6 RBs to 110 RBs corresponding to an overall scalabletransmission bandwidth of roughly 1 MHz to 20 MHz. Each transmissionbandwidth, e.g. 1.4, 3, 5, 10 or 20 MHz, corresponds to a number of RBs.

The basic time-domain unit for dynamic scheduling is one sub-framecomprising two consecutive timeslots. This is sometimes referred to as aresource-block pair. Certain sub-carriers on some OFDM symbols areallocated to carry pilot signals in the time-frequency grid. A number ofsub-carriers at the edges of the transmission bandwidth are nottransmitted in order to comply with spectral mask requirements.

In LTE R8/9 and for R10 (also discussed herein) in single carrierconfiguration where the network may assign the WTRU only one pair of ULand DL carriers (FDD) or one carrier time shared for UL and DL (TDD),for any given subframe there may be a single Hybrid Automatic RepeatreQuest (HARQ) process active for the UL and a single HARQ processactive in the DL.

Buffer status reporting may be used to indicate the amount of data theWTRU has available for transmission to help the eNB choose anappropriate transport block size. BSR may report the buffer status oflogical channel groups (LCG). Logical channels can be divided in up to 4different LCGs through RRC signalling but a logical channel does notnecessarily belong to an LCG.

The following LTE specifications provide a context for describing thevarious methods and approaches set forth herein.

In an LTE MAC specification [36.321], the buffer size of an LCG isdefined as follows:

-   -   Buffer Size: The Buffer Size field identifies the total amount        of data available across all logical channels of a logical        channel group after all MAC PDUs for the TTI have been built.        The amount of data is indicated in number of bytes. It shall        include all data that is available for transmission in the RLC        layer and in the PDCP layer; the definition of what data shall        be considered as available for transmission is specified in [3]        and [4] respectively. The size of the RLC and MAC headers are        not considered in the buffer size computation. The length of        this field is 6 bits. If extendedBSR-Sizes is not configured,        the values taken by the Buffer Size field are shown in Table        6.1.3.1-1. If extendedBSR-Sizes is configured, the values taken        by the Buffer Size field are shown in Table 6.1.3.1-2.

In an LTE RLC specification [36.322], data available for transmission isdefined as:

4.5 Data available for transmission

For the purpose of MAC buffer status reporting, the UE shall considerthe following as data available for transmission in the RLC layer:

-   -   RLC SDUs, or segments thereof, that have not yet been included        in an RLC data PDU;    -   RLC data PDUs, or portions thereof, that are pending for        retransmission (RLC AM).

In addition, if a STATUS PDU has been triggered and the status prohibittimer is not running or has expired, the UE shall estimate the size ofthe STATUS PDU that will be transmitted in the next transmissionopportunity, and consider this as data available for transmission in theRLC layer.

In PDCP specification [36.323], data available for transmission isdefined as:

4.5 Data available for transmission

For the purpose of MAC buffer status reporting, the UE shall considerPDCP Control PDUs, as well as the following as data available fortransmission in the PDCP layer:

For SDUs for which no PDU has been submitted to lower layers:

the SDU itself, if the SDU has not yet been processed by PDCP, or

the PDU if the SDU has been processed by PDCP.

In addition, for radio bearers that are mapped on RLC AM, if the PDCPentity has previously performed the re-establishment procedure, the UEshall also consider the following as data available for transmission inthe PDCP layer:

For SDUs for which a corresponding PDU has only been submitted to lowerlayers prior to the PDCP re-establishment, starting from the first SDUfor which the delivery of the corresponding PDUs has not been confirmedby the lower layer, except the SDUs which are indicated as successfullydelivered by the PDCP status report, if received:

the SDU, if it has not yet been processed by PDCP, or

the PDU once it has been processed by PDCP.

In an LTE specification, the Logical Channel Prioritization (LCP)procedure is specified as follows [36.321]:

5.4.3.1 Logical channel prioritization

The Logical Channel Prioritization procedure is applied when a newtransmission is performed.

RRC controls the scheduling of uplink data by signalling for eachlogical channel: priority where an increasing priority value indicates alower priority level, prioritisedBitRate which sets the Prioritized BitRate (PBR), bucketSizeDuration which sets the Bucket Size Duration(BSD).

The UE shall maintain a variable Bj for each logical channel j. Bj shallbe initialized to zero when the related logical channel is established,and incremented by the product PBR×TTI duration for each TTI, where PBRis Prioritized Bit Rate of logical channel j. However, the value of Bjcan never exceed the bucket size and if the value of Bj is larger thanthe bucket size of logical channel j, it shall be set to the bucketsize. The bucket size of a logical channel is equal to PBR×BSD, wherePBR and BSD are configured by upper layers.

The UE shall perform the following Logical Channel Prioritizationprocedure when a new transmission is performed:

-   -   The UE shall allocate resources to the logical channels in the        following steps:    -   Step 1: All the logical channels with Bj>0 are allocated        resources in a decreasing priority order. If the PBR of a radio        bearer is set to “infinity”, the UE shall allocate resources for        all the data that is available for transmission on the radio        bearer before meeting the PBR of the lower priority radio        bearer(s);    -   Step 2: the UE shall decrement Bj by the total size of MAC SDUs        served to logical channel j in Step 1

NOTE: The value of Bj can be negative.

-   -   Step 3: if any resources remain, all the logical channels are        served in a strict decreasing priority order (regardless of the        value of Bj) until either the data for that logical channel or        the UL grant is exhausted, whichever comes first. Logical        channels configured with equal priority should be served        equally.

LTE-Advanced with Carrier Aggregation (LTE CA R10) is an evolution thataims to improve single carrier LTE data rates using, among otherapproaches, bandwidth extensions also referred to as Carrier Aggregation(CA). With CA, the WTRU may transmit and receive simultaneously over thePhysical Uplink Shared CHannel (PUSCH) and the Physical Downlink SharedCHannel (PDSCH) (respectively) of multiple serving cells; up to foursecondary serving cells (SCells) may be used in addition to a Primaryserving Cell (PCell), thus supporting flexible bandwidth assignments upto 100 MHz. Uplink Control Information (UCI), which may comprise HARQACK/NACK feedback and/or Channel State Information (CSI), may betransmitted either on Physical Uplink Control CHannel (PUCCH) resourcesof the PCell or on PUSCH resources available for a serving cellconfigured for uplink transmissions.

The control information for the scheduling of PDSCH and PUSCH may besent on one or more Physical Data Control CHannel(s) (PDCCH); inaddition to the LTE R8/9 scheduling using one PDCCH for a pair of UL andDL carriers, cross-carrier scheduling may also be supported by a givenPDCCH, allowing the network to provide PDSCH assignments and/or PUSCHgrants for transmissions in other serving cell(s).

For a FDD LTE R10 WTRU operating with CA, there may be one HARQ entityfor each serving cell, where each entity may have up to 8 HARQprocesses, e.g., one per subframe for one round-trip time (RTT); it alsomeans that there may be more than one HARQ process active for the UL andfor the DL in any given subframe, but there may be at most one UL andone DL HARQ process per configured serving cell.

In LTE R8/9/10+ the PDCCH is used by the network (NW or eNB) to assignresources for downlink transmissions on the PDSCH and to grant resourcesfor uplink transmissions on the PUSCH to the terminal device (WTRU).

A WTRU can request radio resources for an uplink transmission by sendinga scheduling request (SR) to the eNB; the SR may be transmitted eitheron dedicated resources (D-SR) on the Physical Uplink Control CHannel(PUCCH) if configured, or using the Random Access procedure (RACH)otherwise (RA-SR).

The eNB may grant radio resources to the WTRU for a transmission onPUSCH, indicated either in a grant received on the PDCCH in configuredresources (a Semi-Persistently Scheduled UL grant).

The WTRU may include, in an uplink transmission, a Buffer Status Report(BSR), indicating the amount of data in the WTRU's buffer. The triggerto transmit a BSR may trigger a scheduling request.

The WTRU determines whether or not it needs to act on control signalingin a given sub-frame by monitoring the PDCCH for specific data controlinformation messages (DCI formats) masked using a known radio networktemporary identifier (RNTI) in specific locations, or search space,using different combinations of physical resources (i.e. control channelelements—hereafter CCEs) based on aggregation levels (AL, eachcorresponding to either 1, 2, 4, or 8 CCEs). A CCE comprises 36 QPSKsymbols, or 72 channel coded bits.

Scheduling control information contained in an uplink grant includes aNew Data Indicator (NDI) which is used to determine whether the grant isfor an initial transmission or for a retransmission, a resourceassignment that indicates what physical resources blocks (PRBs) in timeand frequency are allocated to the transmission and a Modulation andCoding Scheme (MCS). A WTRU can determine the size of the associatedtransport block (TB) from the MCS and the number of PRBs allocated tothe transmission.

In LTE R12 (or later, for aspects of multi-cell operation usinginter-eNB carrier aggregation), the WTRU may be configured with someform of dual connectivity, e.g. a configuration whereby the WTRU mayhave access to resources of cells associated to different eNBs. Thenetwork may control connectivity using a single MME/S1-c connectionterminating in the MeNB.

From the perspective of the control plane, the WTRU may have establisheda RRC connection with a first eNB (i.e. a MeNB) and may additionallysupport a configuration where one or more cells may be associated to asecond eNB (i.e. a SeNB). If it is assumed that the RRC connectionterminates in the MeNB, then the complete message may be received by theRRC entity in the MeNB.

From the perspective of the user plane architecture, the network mayterminate S1-u in the MeNB only (alternative 3 including alternative a,e.g. for all EPS bearers) or it may (e.g. additionally) terminate S1-uin the SeNB (alternative 1A, for one or more EPS bearer).

From the perspective of the L2 transport of SRB data and/or user planetraffic, data for a given radio bearer may be transmitted from thenetwork to the WTRU using a single L2 path or alternatively using eitherL2 path (referred to as DL multi-flow). Similarly, data transmitted maybe transmitted from the WTRU to the network using a single L2 path orusing either L2 path (referred to as UL multi-flow). Multi-flow may berealized by configuration of a bearer such that it may conceptually bemapped to different cells associated to more than one eNB.

A typical transport bearer function may be modeled as a combination ofQuality-of-Service (QoS) related aspects as well as in terms of arouting function. QoS-related aspects may be parameterized in terms of(e.g. maximum or guaranteed) bit rate, maximum tolerable latency or thelike. Routing for a bearer is typically achieved using some form ofphysical or logical (e.g. such as using a tunneling function based onGTP-u or based on an IP tunnel) point-to-point transport path.

The terms “primary MAC entity” and “Secondary MAC entity” herein refereither to MAC entities as separate processes each conceptuallyassociated to cells of different eNBs (e.g. a MeNB and a SeNB), andconsequently to their respective associated L1/physical layerprocessing, or to a single MAC entity which makes the distinctionbetween a Uu (L1/PHY) conceptually associated to a first eNB (e.g. aMeNB) and to a second eNB (e.g. a SeNB). The WTRU may have one primaryMAC entity associated to the MeNB and one secondary MAC entityassociated to a SeNB.

The Primary MAC entity may correspond to the MAC entity that isconfigured with the PCell on which the WTRU established the RRCconnection (as per the legacy R10 definition of the PCell). TheSecondary MAC entity may also be configured with a special cell, inwhich case such cell may be configured with an uplink carrier and withadditional PUCCH resources.

Additional Information on Transmission Timing for Systems such as LTESystems: A WTRU may set its initial DL timing by detecting the PrimarySynchronization Signal (PSS) and the Secondary Synchronization Signal(SSS) in a cell and by determining the first (or best received) path ofthe DL subframe boundaries. The WTRU then may maintain DLsynchronization by measuring the first path arrival of synchronizationsignals and/or DL reference signals. Once the WTRU has acquired DLsynchronization, the WTRU may determine the uplink timing for itstransmissions using the random access procedure, during which the WTRUmay first transmit a preamble on the Physical Random Access Channel(PRACH). The WTRU may align the transmission of the preamble with thestart of the received DL subframe boundary (e.g. such that no timingadvance is applied). The WTRU may receive a random access response (RAR)that includes a Timing Advance Command (TAC). Such TAC may include avalue calculated by the eNB based on the reception time of the preamblee.g. such that the eNB can estimate the two-way propagation delaybetween the eNB and the concerned WTRU, and then determine a suitablevalue to transmit to the WTRU. The WTRU may then use this value todetermine how much in advance of the DL subframe boundary it may startits uplink transmissions. Alignment of uplink transmissions for allWTRUs in a cell may help lower the levels of interference perceiver inthe receiver in the eNB for the cell, in particular when thetransmission timing is less than or equal to a predefined value.

Once a WTRU has initial uplink timing, further adjustments may be neededover time as a result of WTRU movement, changing multipath (i.e. changein the timing of the best received DL path), oscillator drift and/orDoppler shift. To this extent, the WTRU may track the DL timingreference and may perform some adjustments autonomously while the eNBmay monitor the arrival time of the WTRU's uplink transmissions e.g.based on uplink demodulation reference signals, SRS or any othertransmissions such that it may signal TA adjustments in downlinktransmissions using a TAC MAC control element (CE). The WTRU may applythe signaled adjustments received in subframe N exactly at (or no laterthan) the beginning of subframe N+6.

The WTRU may maintain a stored value (Nta) for a Timing Advance Group(TAG). The WTRU may update Nta for the concerned TAG when it receives aTAC from the eNB that indicates a positive or a negative value. The WTRUadditionally also may autonomously update the stored value to compensatefor changes to the received downlink timing e.g. based on its trackingof the DL timing reference. The Nta may be used to adjust the uplinktransmission time in-between reception of TAC and when the TimingAdvance Timer (TAT) is running.

The WTRU may have a configurable timer, the Timing Advance Timer (TAT)per Timing Advance Group (TAG). The WTRU may determine from the TATwhether (if running) or not (otherwise) it may consider itself as havingproper UL timing alignment. When the TAT is not running, the WTRU maynot perform any transmission in the uplink except for the transmissionof a random access preamble. The WTRU may start or restart the TAT whenit receives a TAC, either in a TAC MAC CE or in a RAR. When the TATexpires, the WTRU may consider that it no longer has valid uplink timingalignment for the concerned TAG. The eNB may keep a WTRU uplink timealigned by timely transmission of MAC TAC CE to the WTRU, i.e. beforethe TAT expires in the WTRU.

Efforts are being deployed to create different means to aggregateresources from different eNBs (e.g. R12 LTE inter-eNB aggregation usingdual connectivity). The objective is typically to enable means for anoperator to offload some traffic from a macro cell/eNB to anothercell/eNB which cell may possibly offer some form of hot spot overlaynetwork, or to enable higher throughput.

A WTRU may be configured for dual connectivity. Dual connectivity may beconfigured by the network either for throughput benefits (mainly for thedownlink) or for offload purposes (relieving an eNB deployed for macrocoverage from user plane traffic towards another eNB deployed forcapacity enhancements). When a WTRU is configured for operation withdual connectivity, it may use radio resources associated to differenteNBs where the interface corresponding to each set of resources isherein referred to as a Uu interface. Each Uu interface may itself beconfigured with one or a plurality of serving cells in cases whereintra-eNB carrier aggregation is also supported. The WTRU may then bescheduled for any type of data by a Macro eNB (MeNB) which eNB controlsthe RRC connection, as well as by a Secondary eNB (SeNB) which may beused for exchanging user plane data. This form of dual connectivity mayalso be referred to as Inter-eNB Carrier Aggregation (inter-eNB CA). Inthis case, the WTRU may be configured with different MAC entities, onefor each configured Uu interface.

FIG. 2 illustrates an example system 200 operating using dualconnectivity. System 200 includes a WTRU 210, a MeNB 220, and a SeNB230. WTRU 210 is configured for dual connectivity operation and maytransmit simultaneous and/or overlapping uplink communications to bothMeNB 220 and SeNB 230 as discussed further herein. It is noted that insome implementations, dual connectivity may be conceptualized assimultaneous and/or overlapping communications to more than one MACentity or using the uplink resources of more than one cell group (CG)rather than to more than one eNB.

Support for inter-eNB CA may be according to different possiblearchitectures. A first example architecture (herein referred to as 1A)may support S1-u split, i.e. where an EPS bearer for user plane trafficis associated to a single eNB with PDCP terminating in the concerned eNBfor each corresponding data radio bearer (DRB). A second examplearchitecture (herein referred to as 3C) may support a single 1-utermination in the MeNB for user plane traffic with PDCP terminating inthe MeNB for all DRBs. For both alternatives, the control planeterminates in the MeNB. Additionally, data associated to signaling radiobearers (SRBs) may only be transmitted using the Uu interface associatedwith the MeNB.

From the perspective of the physical layer, a WTRU configured with dualconnectivity may possibly receive downlink data from both eNBssimultaneously, i.e. it can be assumed that no scheduling restrictionprecludes that for at least some subframes the WTRU may be scheduled fora downlink transmission from both eNBs. One implication is that each ofthe MAC/PHY instances may monitor PDCCH and receive PDSCHsimultaneously.

Still from the perspective of the physical layer, different alternativesare possible for uplink operation for a WTRU configured with dualconnectivity. Which alternative may be applicable may depend on a numberof aspects including what may be assumed in terms of timing alignmentbetween cells of different eNBs of the same WTRU configuration. Forexample, different approaches may perform better depending on whether ornot synchronization of symbols in the uplink at the subframe boundarymay be guaranteed at least within a certain margin e.g. such as withinthe length of a cyclic prefix.

In particular, transmissions associated to different physical layers(e.g. different Uu interfaces, and/or associated MAC entities, and/ordifferent eNBs) may occur simultaneously such that their respectivesubframe timing is either synchronized (i.e. their respective timing iswithin a certain margin, which margin does not exceed that specified fortransmissions associated to a single MAC entity) or unsynchronized(i.e., otherwise).

For the synchronized case, a simultaneous transmission may refer to atleast the part of both transmissions that overlaps for a given TTI.

For the unsynchronized case, the timing of a subframe associated to afirst MAC entity may partly overlap with the end of a subframeassociated to a second MAC entity as well as with the beginning of thesubsequent subframe associated to that second MAC entity; in this case,a simultaneous transmission may refer either to the entire overlappingpart (e.g. at symbol granularity and/or across subframe boundary) or toa partial overlap (e.g. at most one subframe is considered for each MACentity). In this case, for some methods described herein, a WTRU maytake into account transmissions over more than one subframe for thesecond MAC entity when such occur simultaneously to a transmission in asubframe of a first MAC entity.

FIG. 3 illustrates example simultaneous transmissions for a synchronizedcase. Transmissions i and j in this example are directed towarddifferent eNBs. The eNBs may be a MeNB and a SeNB such as MeNB 220 andSeNB 230 of FIG. 2 for example. The difference in time 320 between starttime 310 of transmission j and start time 330 of transmission i iswithin (i.e. less than) a threshold for the synchronized case. In thesynchronized case, at least the portions of transmissions i and joccurring during the overlapping time interval 340 may be considered tobe a simultaneous transmission. It is noted that in someimplementations, transmissions i and j may be considered ascorresponding to different MAC entities, or performed using the uplinkresources of different cell groups (CGs) rather than as directed towarddifferent eNBs.

FIG. 4 illustrates example simultaneous transmissions for anunsynchronized case. Transmissions i and j in this example are directedtoward different eNBs. The eNBs may be a MeNB and a SeNB such as MeNB220 and SeNB 230 of FIG. 2 for example. The difference in time 420between start time 410 of transmission j and start time 430 oftransmission i is outside (i.e. greater than) the threshold for thesynchronized case. In the unsynchronized case, the portions oftransmissions i and j occurring during the overlapping time interval 440may be considered to be a simultaneous transmission. In someimplementations, both the portions of transmissions i and j occurringduring the overlapping time interval 440 and the portions oftransmissions i and j−1 occurring during the overlapping time interval420 may be referred to as a simultaneous transmission. It is noted thatin some implementations, transmissions i and j may be considered asdirected toward different MAC entities, or different cell groups (CGs)rather than toward different eNBs.

Possible alternatives for uplink operation for a WTRU configured withdual connectivity, when considering PUSCH, PRACH, SRS and PUCCH, includethe following cases:

Case 1—No simultaneous transmissions or overlap (restrictions atsubframe/symbol granularity).

This may be achieved by precluding simultaneous transmissions bydifferent MAC/PHY instances of the WTRU, e.g. using a Time-DivisionMultiplexing (TDM) approach e.g. as a function of subframe allocationand/or prioritization of different signals according to specific rules.Power scaling rules/prioritization between transmissions associated todifferent MAC/PHY instances (e.g. across different Uu interfaces) maynot be required in such case.

Thus in case 1, TDM and priority rules, e.g. per subframe, are applied.

With case 1, TDM may be applied using priority rules applicable on atime unit basis e.g. at the multi-subframes (e.g. a radio frame)granularity, at the subframe granularity or even at the symbol level.This may avoid power issues or a need for new scaling rules. This may besuitable for synchronized physical layer interfaces.

Case 2—Restricted simultaneous uplink transmissions (restrictions atphysical channel granularity).

This may be achieved by precluding simultaneous transmissions forcombinations of different uplink physical channels, e.g. for differentcombinations of PUSCH, PRACH, SRS and PUCCH e.g. as a function ofsubframe allocation and/or prioritization of different signals accordingto specific rules. Power scaling rules/prioritization betweentransmissions associated to different MAC/PHY instances (e.g. acrossdifferent Uu interfaces) may be required for specific combinations.

Thus in case 2, TDM and priority rules on physical channels, e.g.applied per subframe, and some power-related methods are applied.

With case 2, TDM may be applied using priority rules applicable tophysical channels on a time unit basis e.g. at the multi-subframes (e.g.a radio frame) granularity, at the subframe granularity or even at thesymbol level; some methods still needed to address residual powerissues. This may be suitable for synchronized physical layer interfaces.

Case 3—Unrestricted operation (restrictions at the level of powerallocation and scaling rules only).

This may be achieved by the WTRU applying specific power scaling rules.

Thus in case 3 only power-related methods are applied. This may besuitable for both cases of either synchronized or unsynchronizedphysical layer interfaces.

Some prioritization and power scaling mechanisms have been specified forLTE R10 for intra-eNB carrier aggregation. However a number of aspectsremain problematic. One such aspect relates to characteristics of theinter-eNB CA principles, including the minimal (if any) coordinationbetween schedulers as well as the characteristic that control plane datamay only be transmitted using a single Uu interface i.e. using theresources associated with the MeNB. Another such aspect is the differentexample architectures 1A and 3C (as discussed above, supporting S1-usplit for 1A, and supporting a single S1-u termination for 3C) areapplicable to dual connectivity, as described above, including whetheror not data from a DRB may be received from a single eNB or from both.Additional considerations may also be introduced for alternative 3C ifDRB data in the uplink may only be transmitted on a single Uu (e.g.using resources of the SeNB).

Methods and devices to enable dynamic operation of TDM, transmissionprioritization and transmission power scaling principles and methods maybe needed to avoid starvation or unnecessary delaying of transmission onthe different interfaces. In addition, what rule to apply may vary basedon time, scheduler implementation, ongoing procedure or even type ofdata to transmit.

Methods and devices described in this document relate to enablingefficient offloading and/or efficient aggregation of resources byproviding for the WTRU to coordinate uplink transmissions wheninteracting with different schedulers, one for each eNB associated withthe WTRU's configuration, for example, as shown and described withrespect to FIG. 2.

While methods and devices described herein, including generalprinciples, methods and related embodiments, are described with respectto the 3GPP LTE technology and related specifications, they may beequally applicable to any wireless technology which implements methodsfor accessing multiple wireless layers and/or for connecting to multipleradio access technologies, such as other 3GPP technology based on Wifi,WCDMA, HSPA, HSUPA and HSDPA.

For example, the terms “MAC entity”, “MAC instance”, “MAC”, cell group(CG) or primary/secondary or the like as used herein may be used inreferring to a power allocation function of different radio accesstechnologies. For example, in some embodiments a “primary MAC instance”or a “MeNB CG—MCG” may correspond to a first radio access technologysuch as LTE while a “secondary MAC instance” or a “Secondary CG—SCG” maycorrespond to a second radio access technology such as HSPA or Wifi.

In addition, while they may be described in terms of connectivity to twoeNBs, the methods and devices described herein are also applicable tooperation using an arbitrary number of Uu interfaces (e.g. radio linktowards multiple eNBs).

In the following discussion, the terms “lower” and “higher” are used tomean “lowest” or “lower than another element using similar priorityassessment principles” and “highest” or “higher than another elementusing similar priority assessment principles”. In addition, the terms“PDCCH” and “ePDCCH” will be used interchangeably with the understandingthat any method or device described herein may be applicable to eithertype of control channel, when appropriate.

In this document, the term MAC entity is used mainly to refer to theWTRU's functions for handling transmissions to/from a specific eNB andmay thus refer to the combination of the MAC and any associated physicallayer aspect, to physical layer functions only or to the MAC functionsonly depending on the context.

Prioritization functions are described further herein and may be onepossible approach to enabling a WTRU to overcome conflicting schedulingrequirements in UL.

For example, a WTRU may be configured for dual connectivity. The WTRUmay, in a given transmission time interval (TTI) or subframe, apply aprioritization function for one or more uplink transmissions. The WTRUmay apply a prioritization function by considering more than oneoverlapping subframe associated to the other MAC entity, in particularin case of unsynchronized physical layers. Described herein are examplesof such functions, possible configuration aspects, as well as inputs tosuch functions in terms of how a WTRU may determine the (absolute orrelative) priority associated to the uplink transmissions, schedulinginstructions or combinations thereof.

In particular, prioritization herein may include a function applied by aWTRU when the combination of more than one uplink transmission mayimpair the WTRU's ability to adequately perform such transmissions. Forexample, such impairments may include where a WTRU is unable to complyfor specific combinations of transmissions (e.g. due to some hardwarelimitation, insufficient WTRU capabilities or the like), or where theavailable transmit power for two or more uplink transmission(s) may beinsufficient in a given time interval to perform all expectedtransmissions (e.g. according to applicable scheduling instructions).

For example, such prioritization function may be applied according to atleast one of the following:

-   -   a. When the WTRU is expected to perform at least one        transmission associated to more than one MAC entity, and such        transmissions overlap at least partly (e.g. either at the        subframe level or at the symbol granularity).    -   b. When the WTRU may possibly perform at least one transmission        associated to more than one MAC entity, and such transmissions        overlap at least partly (e.g. either at the subframe level or at        the symbol granularity) including overlapping subframes for        which the WTRU is in DRX Active Time for both MAC entity.    -   c. In any subframe for which the WTRU performs at least one        transmission.

In some methods, using any of the above methods, a subframe may beadditionally excluded when at least one of the following conditions ismet for at least one of the MAC entity:

-   -   a. The WTRU is not in DRX Active Time.    -   b. The WTRU may not perform an uplink transmission due to the        occurrence of a measurement gap.    -   c. The WTRU is not expected to perform any uplink transmission        e.g. due to an interruption introduced by the MAC        activation/deactivation function such as activation time        following the reception of a MAC Activation CE that activates at        least one cell of the concerned MAC entity.    -   d. The WTRU is not expected to perform any uplink transmission        e.g. due to an interruption introduced by processing required        for an RRC procedure such as a reconfiguration procedure, or        such as a RRC re-establishment procedure.    -   e. The WTRU is not expected to perform any uplink transmission        e.g. due to the WTRU not having valid uplink timing advance for        the special cell of the concerned MAC entity (e.g. PCell for the        MeNBr Cell Group, pSCell for the SeNB Cell Group).    -   f. The WTRU is not expected to perform any uplink transmission        due to some impairment e.g. such as when detecting radio link        failure for the physical layer associated to the concerned MAC        entity.

In some methods, in subframes for which the WTRU does not apply suchprioritization function, consequently the WTRU may instead use abehavior similar to a behavior used for single connectivity e.g. theWTRU may apply legacy power control and power allocation functions.

FIG. 5 is a flowchart 500 illustrating an example application of aprioritization function. On a condition 510 that a WTRU is configuredfor operation in a dual connectivity mode, the WTRU may determine instep 530 whether the simultaneous transmission of the plurality oftransmissions scheduled for uplink in the time interval would exceed acapability of the WTRU.

If the WTRU capability would be exceeded, the WTRU may apply aprioritization function 540 and may proceed to transmit the uplinktransmissions according to the prioritization in step 550.

If the combination of uplink transmissions do not exceed a capability ofthe WTRU to perform all of the uplink transmissions, the WTRU may instep 560 transmit the uplink transmissions per MAC entity withoutapplying a prioritization function.

It is noted that in some implementations of the application of theprioritization function illustrated in FIG. 5, the uplink transmissionsmay be conceptualized as transmissions to more than one eNB, or asuplink transmissions using the resources of more than one CG, ratherthan corresponding to more than one MAC entity.

Methods for selective transmission are also further described herein.

One way to realize a prioritization function is through selectivetransmission. For example, a transmission may be performed byselectively determining what grant information to use for a HARQ processassociated to the transmission of a transport block (TB). A TB may beassociated to a specific TB size (TBS) which may represent the amount ofdata information bits as provided by the MAC layer. The WTRU maydetermine the TBS as a function of the MCS and the number of PRBsassociated to the transmission.

The WTRU may autonomously determine to use one of a plurality ofavailable sets of grant parameters. More specifically, the WTRU maydetermine that it should perform a transmission such that it mayautonomously determine one or more characteristics of the transmissionas a replacement of one or more aspects of the applicable grant (the“base grant”). Such characteristic(s) may include parameter(s)associated to a grant. The WTRU may first determine one (or more)alternative values for the concerned characteristic(s). Such alternativevalue(s) may be grouped as sets of parameters. One such grouping maycorrespond to the definition of a grant for an uplink transmission (an“alternative grant”). Such set or sets may be associated to a servingcell of the WTRU's configuration. Such set or sets may have anassociated validity criterion which may be modified with time explicitly(e.g. from signaling received from an eNB e.g. the MeNB) or implicitly(e.g. based on subframe timing, expiration, or the like).

The WTRU may autonomously determine to replace base grant information byan alternative grant. For example, when the WTRU applies aprioritization function according to a selective transmission method, itmay use an alternative grant instead of the base grant for a giventransmission.

Possibly, the WTRU may not replace a grant received in a RAR. It is alsopossible that a WTRU may only replace a base grant received usingspecific DCI types with an alternative grant. For example, the WTRU mayonly replace a base grant if it is received in a DCI format e.g. DCIformat 0. In another example, a WTRU may not replace a base grantreceived in a RAR with an alternative grant.

The set of parameters, or grant, may be associated to a specific TBsize. It is also possible that such set or sets of parameters (e.g. analternative grant) may be associated with a transport block (TB) size,e.g. such that for a given transport block size the WTRU may determinethat it has one or more alternative grants.

The following relates to example rules for grant substitution in thecase of a new transmission or new HARQ process. Several approaches forrealizing a prioritization function using grant substitution arepossible.

New transmission—no restriction in TBS: In one example approach, theWTRU may replace a base grant with an alternative grant for a newtransmission independently of their respective associated TBS.

Further logic for the concerned process: In such cases, the WTRU mayselect an alternative grant and determine the associated TBS. The WTRUmay then perform the new transmission on the resource and with the MCSindicated in the alternative grant. Adaptive retransmissions may then beperformed on the resource and, if provided, with the MCS indicated onPDCCH only if the resulting TBS is identical to the TBS associated tothe initial transmission for this TB (otherwise, this is a caseaddressed further below regarding DCI indication of NDI toggling).Non-adaptive retransmissions may be performed on the same resource andwith the same MCS as was used for the last made transmission attempt.

New transmission—restricted to same TBS as base grant only: In anotherexample approach, the WTRU may replace a base grant with an alternativegrant for a new transmission, where the WTRU only uses an alternativegrant having the same associated TBS as the concerned base grant.

If only alternative MCS then determine alternative set of PRBs: In suchcase, the WTRU may select the alternative grant. If only an alternativeMCS is available, the WTRU may determine an associated set of resourcesautonomously. If there exists one combination of the alternative MCSwith the PRBs indicated in the base grant for the concerned TBS, thenWTRU may use such PRBs; otherwise, the WTRU may determine a differentset of PRBs. Such different set of PRBs may represent a smaller numberof PRBs and may be entirely overlapping with the set of PRBs indicatedby the base grant and using the same starting resource element for theinitial PRB.

If only alternative PRBs then determine alternative MCS: In such cases,the WTRU may select the alternative grant. If only an alternative set ofPRBs is available, the WTRU may determine the associated MCSautonomously: if there exists one combination of the alternative set ofPRBs with the MCS indicated in the base grant for the concerned TBS,then WTRU may use such MCS; otherwise, the WTRU may not select thealternative grant. Alternatively, the WTRU may determine such differentMCS using a different set of PRBs that may represent a smaller number ofPRBs and may be entirely overlapping with the set of PRBs indicated bythe alternative grant and using the same starting resource element asindicated by the alternative grant.

Further logic for the concerned process: The WTRU may then perform thenew transmission on the resource and with the MCS as determined in theabove described steps. Adaptive retransmissions may then be performed onthe resource and, if provided, with the MCS indicated on PDCCH only ifthe resulting TBS is identical to the TBS associated to the initialtransmission for this TB (otherwise, this is a case addressed furtherbelow regarding DCI indication of NDI toggling). Non-adaptiveretransmissions are performed on the same resource and with the same MCSas was used for the last made transmission attempt.

In an example approach, the WTRU may replace a grant (i.e. either a basegrant e.g. for an adaptive retransmission or an alternative grant e.g.for a non-adaptive retransmission) for a retransmission for an ongoingHARQ process using another alternative grant only if the associated TBSif the same as the TBS of the grant it replaces and/or as the TBS of thelast made transmission attempt.

Rules for grant substitution—retransmission for an ongoing HARQ process:For example, the WTRU may perform one or more HARQ retransmissionsassociated with the same HARQ process (i.e. for retransmission of thesame TB). The WTRU may then only select an alternative grant (ifapplicable) having a TBS which is the same as the TBS of the previoustransmission attempt for this process independently of whether a basegrant or an alternative grant was used.

A possible approach for handling redundancy version for a HARQ processusing an alternative grant: In legacy LTE systems, the sequence ofredundancy versions is 0, 2, 3, 1. The WTRU typically maintains avariable CURRENT_IRV as an index into the sequence of redundancyversions. This variable is updated modulo 4. The WTRU may use this samelogic even for a HARQ process for which selective transmission and theuse of alternative grant information is applicable.

Possible approach for handling other control information from a basegrant when replacing with an alternative grant: The WTRU may comply withsome of the downlink control information received in the DCI thatcontains the base grant even if the transmission for PUSCH is performedusing the alternative grant.

Possible WTRU behavior for TPC command for PUSCH: The WTRU may determinethat the DCI that contains the base grant also includes TPC command bitsfor power control of PUSCH. In an example approach the WTRU may complywith the TPC command independently of whether or not an alternativegrant is used for the associated transmission.

Possible WTRU behavior for CSI/SRS triggers: The WTRU may determine thatthe DCI that contains the base grant also includes bits that are setsuch that the WTRU is requested to transmit CSI information and/or SRS(e.g. SRS trigger type 1). In this situation, in an example approach, ifthe WTRU replaces such base grant with an alternative grant, the WTRUmay determine that the request is applicable to the alternative grant.

Possible WTRU behavior for SRS triggers: The WTRU may comply with anaperiodic SRS request in DCI independently of selected grant. In anotherapproach, the WTRU may determine that it should transmit a SRS accordingto a trigger, e.g. either trigger type 0 (L3/RRC trigger) or triggertype 1 (L1/DCI trigger) independently of the type of grant used for thePUSCH transmission. The WTRU may additionally apply anotherprioritization function to the SRS transmission as described herein.

For example, the WTRU may receive a grant for a PUSCH transmission in aDCI on PDCCH which DCI may include a SRS request (e.g. the bit for SRSrequest is set). In this case, the WTRU may select an alternative grante.g. according to any of the methods described herein and perform thetransmission of SRS according to the request in the base grant.

In another approach, the WTRU may ignore any trigger to transmit SRSwhen it uses an alternative grant. This may lower possible interferencewith transmission from other WTRUs.

Possible WTRU behavior for CSI triggers: The WTRU may comply with anaperiodic CSI request in DCI independently of selected grant. The WTRUmay determine that it should perform the transmission of CSI accordingto an aperiodic request independently of the type of grant used for thePUSCH transmission. The WTRU may additionally apply anotherprioritization function or functions to the CSI transmission asdescribed herein.

For example, the WTRU may receive a grant for a PUSCH transmission in aDCI on PDCCH which DCI may include a CSI request (e.g. at least one bitof the CSI request field is set). In this case, the WTRU may select analternative grant e.g. according to any of the methods described hereinand perform the transmission of CSI according to the alternative grantif the transmission is included in the corresponding PUSCH transmission,or according to legacy methods otherwise (e.g. on PUCCH or on anotherPUSCH).

The WTRU may comply with configured CSI reporting independently ofselected grant: In another approach, the WTRU may determine that itshould perform the transmission of CSI according to a configuration forperiodic CSI reporting independently of the type of grant used for thePUSCH transmission. The WTRU may additionally apply other prioritizationfunction to the CSI transmission as described herein.

The WTRU may ignore any CSI trigger when it selects alternative grant:In another approach, the WTRU may ignore any trigger to transmit CSIwhen it uses an alternative grant. This may simplify blind decodingprocessing in the receiver (eNB).

WTRU behavior for a HARQ process configured with TTI bundling: In oneapproach, a WTRU configured for TTI bundling operation (e.g. in thePCell of the WTRU's configuration for the Primary MAC entity) may applyany of the approaches above to replace the base grant with analternative grant for a bundle transmission. In another approach, a WTRUconfigured for TTI bundling operation for a given serving cell may notselect an alternative grant for any transmission in the concerned cell.

WTRU autonomously used alternative grant, then a received DCI indicatesdifferent TB size: The WTRU may have used an alternative grant for theprevious transmission for a HARQ process. The WTRU may subsequentlyreceive a DCI that indicates a grant for the concerned HARQ process,which grant results in a different TBS than the last made transmissionfor this HARQ process.

Case where DCI indicates that an associated NDI has been toggled: Insuch case, if the WTRU determines that the NDI is considered toggledfrom the decoding of the base grant, the WTRU may determine that thegrant is for a new transmission and consider the base grant as beingvalid scheduling information.

Case where DCI does not indicate that an associated NDI has beentoggled: Otherwise if the WTRU determines that the NDI is not consideredtoggled from the decoding of the base grant, the WTRU may perform atleast one of the following:

The WTRU may determine that the base grant is inconsistent with thestate of the HARQ process (i.e. this may be considered as a new errorcase introduced by loss of synchronization between the WTRU-autonomousbehavior described herein and the eNB scheduling state).

The WTRU may collapse the HARQ process, i.e., the WTRU may determinethat the grant is for a new transmission and may consider the base grantas being valid scheduling information. The WTRU may then consider theNDI as having been toggled. The WTRU may first determine whether or notthe physical hybrid-arq indicator channel (PHICH) associated to the lastmade transmission for this HARQ process indicates ACK or NACK. If NACK,then the WTRU may first determine that the transmission for thetransport block associated to the last made transmission for the HARQprocess has failed, and may perform similar behavior as upon reachingthe maximum number of HARQ transmissions for this HARQ process and/ormay initiate a scheduling request (SR) and/or a random access procedureon PRACH resources associated to the concerned cell and/or to a cell ofthe concerned MAC entity. Alternatively, the WTRU may first determinewhether or not the PHICH associated to the last made transmission forthis HARQ process indicates ACK or NACK. If NACK, then the WTRU mayfirst determine that the transport block (and/or its contents)associated to the last made transmission for the HARQ process is to beretransmitted. Alternatively, the WTRU may, independently of the lastreceived feedback for this HARQ process, first determine that thetransport block associated to the last made transmission for the HARQprocess has failed, and may perform similar behavior as upon reachingthe maximum number of HARQ transmissions for this HARQ process, and/ormay initiate a scheduling request (SR) and/or a random access procedureon PRACH resources associated to the concerned cell and/or to a cell ofthe concerned MAC entity.

The WTRU may discard the received control scheduling information and maysuspend the concerned HARQ process. For example, the WTRU may considerthat the last received feedback for the concerned HARQ process is set toACK. The WTRU may keep the process suspended until it receives controlsignaling from which it may consider that the NDI is toggled. In thiscase, the eNB may detect that the HARQ process is suspended from theabsence of transmission on the scheduled resources. Note: assuming thatan eNB may detect the inconsistency, a WTRU could subsequently receive agrant with correct TBS information and continue the suspended process.

The WTRU may flush the uplink HARQ buffer for the HARQ process. In thiscase, the eNB may detect that the HARQ process is inactive. Possibly,the WTRU considers that the NDI has been toggled for the nexttransmission for this HARQ process.

For a given subframe (e.g. n−4) that collides with a measurement gap andin which the WTRU may have otherwise received dynamic schedulinginformation on PDCCH for a HARQ process, the WTRU may behave accordingto at least one of the following if the last made transmission wasperformed using an alternative grant. In one approach, the WTRU maydetermine that it should perform a non-adaptive retransmission insubframe n if the last received feedback is NACK and according to thelast made transmission using a base grant for this transport block (ifapplicable), otherwise it may refrain from performing any transmissionfor this HARQ process in subframe n. In another approach, the WTRU maydetermine that it should perform a non-adaptive retransmission insubframe n if the last received feedback is NACK and according to thegrant of the last made transmission for this transport block. In anotherapproach, the WTRU may refrain from performing any transmission for thisHARQ process in subframe n if the last made transmission was performedusing an alternative grant, independently of the last received feedback.

For a given subframe (e.g. n) that collides with a measurement gap andin which the WTRU may have otherwise performed a PUSCH transmission fora HARQ process, the WTRU may perform as per legacy behavior.

For a given subframe (e.g. n+4) that collides with a measurement gap andin which the WTRU may have otherwise received PHICH feedback for a HARQprocess, the WTRU may determine that the last received feedback is ACKas per legacy behavior.

The WTRU may associate a priority level with such set of parameters(e.g. with an alternative grant) such that it can determine theapplicable set for the transmission as a function of the transmission'spriority level. The WTRU may determine such priority level using similarapproaches as for determination of priority level for a transmission asdescribed herein.

The WTRU may have multiple UL transmissions granted in the same subframeand may allocate power per a priority rule. Upon satisfying alltransmissions with higher priority, a WTRU may determine the appropriategrant parameters of a lower priority transmission based on the remainingavailable power.

The WTRU may, in one approach, use an alternative grant instead of abase grant only if the base grant indicates that the schedulinginformation is for a new transmission (e.g. where the WTRU determinesthat the NDI bit is considered to have been toggled).

According to another approach, uplink control information (UCI) thatindicates the use of an alternative grant (and possibly, an indicationallowing the eNB to determine one or more aspects of the alternativegrant e.g. an index to an entry in a table) may be added in thecorresponding PUSCH transmission. Such indication may be used by the eNBto determine how to blindly decode the transmission and possibly alsoany retransmissions for the same transport block.

According to another approach, the WTRU may obtain such set oftransmission parameters for a given type of transmission (e.g. PUSCH) tobe performed in a given subframe (e.g. subframe n+4) according to atleast one of the following:

1. Multi-grant in single DCI: The WTRU may receive multiple grants inthe same DCI in subframe n, on a PDCCH that schedules transmission forthe WTRU on a given serving cell of the WTRU's configuration. Forexample, the WTRU may successfully decode one DCI that includes a basegrant as well as one (or more) alternative grant(s). The priority levelassociated with each grant may be determined using any of the methodsdescribed herein, in particular as a function of the order of theparameters (grant information) in the concerned DCI.

2. Multi-DCI/multi-PDCCH: The WTRU may receive multiple grants indifferent DCIs in subframe n, on a PDCCH that schedules transmission forthe WTRU on a given serving cell of the WTRU's configuration. Forexample, the WTRU may successfully decode multiple DCIs—one thatincludes a base grant as well as one (or more) DCI(s) that include analternative grant. Such DCI may include a single alternative grant, or aplurality of alternative grants (in which case the relative prioritylevel between each alternative grants may be a function of theorder/position of the grant in the concerned DCI). The priority levelassociated to each successfully decoded DCI may be determined using anyof the methods described herein, in particular as a function of thesignaling in the DCI (e.g. an explicit indication), of the RNTI used fordecoding the DCI, of the identity of the PDCCH or of the search space onwhich the DCI is successfully decoded.

3. Grant extrapolation: The WTRU may receive a grant in a DCI insubframe n, from which the WTRU may be allowed to derive one or morealternative grant(s) according to specific rules (such that the eNB isexpected to perform blind decoding appropriately). The priority levelassociated to each DCI may be determined using any of the methodsdescribed herein, in particular as a function of the nature of the grante.g. whether the grant is dynamically scheduled or is a semi-staticallyconfigured base grant (for a transmission of higher priority) or anextrapolation thereof (for a transmission of lower priority). Forexample, in the event that a WTRU cannot perform an UL transmission atthe required and/or expected transmission power with the grantedparameters, the WTRU may modify one or multiple parameters of the ULtransmission. For example, a WTRU may be configured with MCS and TBStables such that an indication in a grant maps to a set of possible MCSand/or TBS values. The WTRU may use a different MCS and/or TBS valuebased on being able to achieve the required transmission power. Theselection of the MCS and/or TBS value may be based on satisfying anoptimization function. For example, the WTRU may select the MCS and/orTBS value that is largest, smallest, requires most transmission power,requires least transmission power or preconfigured as a fallback valuefrom the one indicated in a grant. The example provided herein may beapplicable to transmission rank, precoder, cyclic shift for DM-RS andOCC and/or CSI Request;

4. Configured alternative grant: The WTRU may be configured (e.g. byRRC) with a semi-static alternative grant (e.g. some form of persistentalternative grant). This is herein referred to as a configuredalternative grant (CAG). When the WTRU is configured with such grant,the WTRU may select and use the CAG when it determines that it shouldapply a prioritization function for a given transmission. In otherwords, the WTRU may use a CAG instead of another, possibly lesssuitable, grant (e.g. a base grant) for a given transmission. A CAG mayalso be restricted in time, such that it may apply to one or to aplurality of subframes within a certain time interval (e.g. a radioframe) and/or may be available according to a given (possiblyconfigurable) period.

The WTRU may, in some implementations, use such CAG only when the WTRUhas received a DCI that dynamically schedules the correspondingtransmission (i.e. in case of a dynamically scheduled base grant). Inother words, the validity of a CAG may be a function of the WTRU's PDCCHdecoding for the concerned serving cell. The validity of a CAG may alsobe a function of the availability of any base grant for an uplinktransmission for the concerned cell, e.g. including where the WTRU has asemi-persistent grant (i.e., a R8-like semi-persistent scheduling (SPS)grant) for the concerned subframe (i.e. in case of a semi-persistentscheduled grant without dynamic adaptation). In other words, the WTRUmay autonomously adapt a dynamically scheduled transmission (i.e. a basegrant) or a first configured grant for a semi-persistent scheduledtransmission (i.e. a semi-static base grant) by using a secondconfigured (semi-persistent) grant (i.e. an alternative grant).

In some implementations, the WTRU may receive additional controlsignaling that activates and deactivates such CAG. Such signaling may bereceived in a DCI on PDCCH. Such signaling may include the correspondinggrant information for the CAG. The WTRU may transmit HARQ feedback e.g.in subframe n+4 for such control signaling received in subframe n.Alternatively, such signaling may be a L2 MAC Control Element (CE).

In some implementations, the WTRU may determine that it may autonomouslyselect one or more transmission parameters, e.g. that it may replace abase grant with an alternative grant from the reception of an explicitindication in a DCI. Such indication may be a specific value and/orcodepoint in the TPC field of the DCI. According to one possibility, theWTRU may determine that it may autonomously select one or moretransmission parameters only for a DCI for which the WTRU considers thatthe NDI bit is toggled and/or for a DCI indicating a new transmission.The eNB may then detect a situation where a WTRU becomes power limitedand indicate for every new transmission whether or not the WTRU mayautonomously replace a grant. This may be useful in a situation where nospecific priority is associated to any MAC instance but for which theWTRU determines itself how to prioritize uplink transmissions, and alsobecause a scheduler may not know a priori whether or not the WTRU isbeing scheduled for both MAC entities in a given TTI.

In some implementations, the WTRU may determine that there are two ormore of such additional sets of transmission parameter(s) (e.g.alternative grants) that are valid and available in a given subframe(i.e. in addition to the base grant). In such case, the WTRU may selectthe grant that maximizes the allocation of power and/or that minimizesthe scaling of the transmission power e.g. across all transmissions of agiven MAC entity (e.g. if the corresponding transmissions are givenhigher priority in a MAC-specific manner), across all transmission ofthe WTRU for a given subframe, or across types of cell (e.g. PCell ofprimary MAC entity first, then Special cell of secondary MAC entity,SCells of primary MAC instance and finally the remaining SCells).

For example, selective transmission may be useful to perform some formof WTRU autonomous decision to avoid a situation where a WTRU performsblanking of (or scaling to zero power) a transmission, to avoid asituation where power scaling is applied to a transmission, or to avoidtruncating a transmission. The corresponding eNB may perform blinddecoding of the transmission according to two or more grants that may beapplicable in the concerned subframe. The eNB may transmit controlsignaling that activates and deactivates such alternative sets oftransmission parameters or grant(s) e.g. such that those are availableto the WTRU only on a condition that the eNB (e.g. the MeNB) determinesthat the WTRU may be power-limited, or on a condition that processingrequirements for the associated blind decoding in the eNB exceeds thecapabilities of the eNB for a given period. In particular, this may beuseful where it cannot be assumed that timing of the uplink transmissioncan be synchronized within some margin, e.g. at the symbol duration andwithin the length of a cyclic prefix.

From the network perspective, the implication is that the eNB mayperform additional blind detection processing in a subframe for which aWTRU may have one (or more) alternative grant(s) available for a givenHARQ process.

The eNB may perform such blind decoding to detect uplink controlinformation that indicates that an alternative grant is used (andpossibly also, which alternative grant is used) in the PUSCHtransmission (if/when such UCI is applicable) for every concerned suchsubframe.

The eNB may perform such blind decoding of the transport block using thedifferent possible alternatives. In such case, the eNB may perform suchactions only where the transmission of a new transport block is expectedif the WTRU is only allowed to first use an alternative grant for agiven HARQ process for a new transmission (e.g. only where the WTRUdetermines that the NDI associated to the concerned HARQ process hasbeen toggled and/or where the HARQ process obtains a new MAC PDU fortransmission). Otherwise, the eNB may perform such actions also where aretransmission for a transport block may be expected if the WTRU isallowed to use a first alternative grant for a given HARQ process whereapplied to a HARQ retransmission (e.g. where the grant selection isrestricted by the size of the transport block associated to theassociated base grant). If the WTRU may only select an alternative grantof a TBS that matches that of the base grant and/or that of the previoustransmission of the same HARQ process, the eNB may only perform blinddecoding using those alternative grant(s) that matches that TBS if oneor more alternative grant(s) of different TBS are also configured forthe concerned WTRU.

The following relates to various approaches to adaptive prioritization.One example approach for realizing a prioritization function may be todynamically adjust how the prioritization function is applied. The WTRUmay then use a different prioritization function or apply theprioritization function differently such as by allocating transmissionpower in different manner from one time unit (e.g. a TTI, a radio frameor another possibly configured period) to another. Such configuredperiod may include a configured power allocation period. For simplicity,the term TTI may be used below to represent any form of time unit. Suchdynamicity may be introduced using a function that may vary the priorityassociated to one or a subset of transmissions. Such subset may betransmissions associated to a same MAC entity.

FIG. 6 illustrates one example of dynamic adjustment of a prioritizationfunction. Step 640 illustrates an example implementation of aprioritization function, such as may be useable with step 540 shown anddescribed with respect to of FIG. 5. In step 610, the WTRU may determinewhich prioritization function to apply and/or how to apply theprioritization function for the given time interval, and in step 620,the WTRU may apply the determined prioritization function. It is notedthat in other implementations (not shown) the prioritization functionmay be fixed, or may be varied for time intervals other than the giventime interval.

One possible approach is to implement a method that can change thepriority applied to transmissions associated to different MAC entities.Such approach may be useful to realize some form of fairness betweenscheduling events from a plurality of eNBs and may contribute toavoiding starvation that could occur in the presence of uncoordinatedschedulers unaware of each other's impact on the WTRU's transmissions.Such an approach may be useful to realize some form of fairness whenpower allocation is performed according to the principles describedherein where a WTRU simultaneously transmits using physical layersassociated to different radio access technologies.

The approaches described herein may be applicable to the total availableuplink transmission power (e.g. up to P_(CMAX) in the case oftransmissions associated to LTE) or to a portion of the available uplinktransmission power. Such portion may be up to an amount of power forwhich each MAC instance may contend, such as any remaining power that isnot part of an amount that is guaranteed to a specific MAC entity. Theapproaches described herein may be applicable to a subset of thetransmissions of a WTRU, such as transmissions of a specific priority.

For example, one example principle may that “the one who gets penalizedcan change dynamically”. For example, for every TTI that leads to a needto scale the power (a scaling event), power may first be allocated tothe MAC entity with highest priority and remaining power may then beallocated to other MAC entit(y/ies) in decreasing priority order. Thepriority associated to each MAC entity that contends for the totalavailable power may change prior to (or following) every collisionevent, or alternatively prior to (or following) the beginning of aperiod that starts with such collision event. Each MAC instance isallocated a probability of having the highest priority level, whichprobability is updated such that it is increased in case contention islost and such that it is lowered in case contention is won. Theprobability may be updated also after a given period (including possiblyin a periodic manner during periods without contention) without anyscaling event such that the entity with the highest probability isupdated such that it gets lower—and conversely—until each MAC entityreaches a specific value (e.g. an initial possibly configured value oran equal probability for each MAC entity). In a given TTI for which theWTRU determines that scaling is required, the WTRU may first determinewhich MAC entity has highest priority by using a random generator thatuses the probability of each MAC entity as input. For example, in casewhere two MAC entities contend for the total available WTRU transmitpower, the WTRU only needs to maintain a probability and to determinethe priority for a single MAC entity.

In another approach each MAC instance may be allocated a priority value.Upon a collision, the MAC(s) with highest (or lowest) priority value mayperform transmissions without scaling while transmissions associated toother MAC(s) may be scaled. Prior to (or following) a collision, thepriority values of some or all affected MACs may be modified such thatany MAC entity that performed at least one transmission with or withoutscaling may have its priority value increased or decreased(respectively) by a predetermined amount. Furthermore, prior to (orfollowing) a period that starts with such a collision and possiblycontains no other collision, the priority levels of the affected MACsmay increase (or decrease) by a (possibly different) predeterminedamount, such that they may reach a specific value (e.g. an initial valueor an equal probability for each MAC entity).

For conciseness and without limiting the applicability of the methodsdescribed herein to specific transmissions by type of physical channel,by type/identity of a serving cell or for individual transmissions, thefollowing will assume that priority is allocated to all transmissions ofa given MAC entity (unless explicitly stated otherwise). In addition,without limiting the applicability of the methods described herein to anarbitrary number of elements (e.g. more than two transmissions or morethan two MAC entities), the following will assume that transmissionsassociated to two MAC entities are contending for available power. Inaddition, power scaling is used as prioritization function but themethod described herein may be applicable to any other prioritizationfunction.

In an example approach, such method may be applied only in TTIs forwhich the WTRU determines that a prioritization function (e.g. powerscaling) should be applied. For example, such method may be used toassociate varying priority to one or more transmissions. For example,the WTRU may use such method to determine that it will first allocatetransmission power to transmissions associated to one of two MACentities by varying the priority of the concerned MAC entities.

Where power scaling is needed, the WTRU may first determine a priorityfor the applicable MAC entities such that a priority order isestablished, then allocate power to transmissions of the MAC entity withthe highest priority, and any remaining power to the other entitieseither in decreasing priority order or by splitting remaining powerequally to the different MAC entities. In any case, if the poweravailable to a concerned MAC entity is insufficient for alltransmissions, power scaling may be applied to the transmissionsassociated to the concerned MAC entity e.g. according to legacy R11behavior, or more generally according to the power allocation behaviorof the concerned radio access technology once the total amount of WTRUpower available to the concerned MAC entity is determined.

For example, if no power remains for the second MAC entity and if it isinsufficient for all transmissions of the first MAC entity, powerscaling may be applied to transmissions of the first MAC entity e.g.according to legacy R11 power scaling function. If power remains for thesecond MAC entity, power scaling may be applied to transmissions of thesecond MAC entity e.g. according to legacy R11 power scaling function.If power scaling is applied for a SMAC, it may be assumed that one ofthe cells of the concerned MAC entity is a special cell for whichscaling is applied similarly as for the PCell in legacy R11 scaling.

FIG. 7 is a flowchart 700 illustrating an example application ofadaptive prioritization. In 700, a WTRU is configured with a maximumpower for all uplink transmissions during a given time interval (Pcmax),a minimum guaranteed power for uplink transmission from the WTRU usingthe uplink resources of a first cell group CG1, and a minimum guaranteedpower for uplink transmission from the WTRU using the uplink resourcesof a second cell group CG2.

On a condition 710 that the WTRU is configured for operation in a dualconnectivity mode during a particular time interval, the WTRU maydetermine in a step 730 whether the total power required for allunscaled uplink transmissions scheduled for the time interval willexceed Pcmax. If it will not, the WTRU may transmit uplink transmissionswithout applying a prioritization function in step 740.

If the total power required for all unscaled uplink transmissionsscheduled for the time interval will exceed Pcmax, the WTRU may in step750 allocate power to uplink transmissions scheduled for transmission toCG1 up to the minimum guaranteed power for CG1. In some implementationsthese transmissions may be allocated in decreasing priority order and/orby scaling power if the required transmit power for all uplinktransmissions scheduled for transmission to CG1 exceeds the minimumguaranteed power for CG1.

On a condition 760 that no unallocated power remains after allocatingCG1 uplink transmissions, the WTRU may transmit all allocated uplinktransmissions as allocated in step 795. If any unallocated power remainsafter allocating CG1 uplink transmissions (i.e. Pcmax−power allocatedfor uplink transmissions using the uplink resources of CG1>0), the WTRUmay in step 770 allocate power to uplink transmissions scheduled fortransmission using the uplink resources of CG2 up to the minimumguaranteed power for CG2. In some implementations these allocations maybe made to transmissions in decreasing priority order and/or by scalingpower if the required transmit power for all uplink transmissionsscheduled for transmission using the uplink resources of CG2 exceeds theminimum guaranteed power for CG2.

On a condition 780 that no unallocated power remains after allocatingCG2 uplink transmissions, the WTRU may transmit all allocated uplinktransmissions as allocated in step 795. If any unallocated power remainsafter allocating CG2 transmissions (i.e. Pcmax−allocated power foruplink transmissions using the uplink resources of CG1−allocated powerfor uplink transmissions using the uplink resources of CG2>0), theremaining power may be allocated by the WTRU in step 790 for anyremaining unallocated uplink transmissions using the uplink resources ofCG1 or CG2. In some implementations, these allocations may be made totransmissions in decreasing priority order and/or by scaling power.After the remaining unallocated power has been allocated, the WTRU maytransmit all allocated uplink transmissions as allocated in step 795.

FIG. 8 is a block diagram illustrating allocation of power to uplinktransmissions according to the example described with respect to FIG. 7.FIG. 8 shows Pcmax 800, the minimum guaranteed power 810 for uplinktransmissions using the uplink resources of CG1, and the minimumguaranteed power 820 for uplink transmissions using the uplink resourcesof CG2. Minimum guaranteed power 810 and minimum guaranteed power 820are each a ratio (i.e. percentage or proportion) of Pcmax, and FIG. 8illustrates example proportions for an application of the adaptiveprioritization method shown and described with respect to FIG. 7.

For these example proportions, guaranteed power 810 shows the proportionof Pcmax 800 which may be allocated as minimum guaranteed power foruplink transmissions using the uplink resources of CG1 in step 750 ofFIG. 7, and guaranteed power 820 shows the proportion of Pcmax 800 whichmay be allocated as minimum guaranteed power for uplink transmissionsusing the uplink resources of CG2 in step 770 of FIG. 7. 830 willcorrespond to the proportion of Pcmax 800 which may be allocated to anyremaining uplink transmissions in step 790 of FIG. 7 if power isallocated for CG1 and CG2 transmissions each at the minimum guaranteedpower.

In one example approach, adaptation may be derived randomly. Forexample, the WTRU may use a stateless and fair probability function. Theoutcome of the function (e.g. similar to the toss of a coin) may beapplied to determine the priority associated to each MAC entity. Forexample, the WTRU may apply the probability function (e.g. a Bernoullidistribution with probability=0.5) to one of two MAC entities; if theconcerned MAC entity gets associated to value 1, then all transmissionsassociated to this MAC entity are allocated power first; if any powerremains, transmissions associated to the second MAC entity may beallocated remaining power. This may be generalized to any number of MACentities using the appropriate probability distribution.

In an example approach that may generalize the previous approach, suchprobability function may use a different probability for the respectiveMAC entities. For example, the WTRU may apply the probability function(e.g. a Bernoulli distribution with probability=x) to one of two MACentities, where x is in the range [0, 1]. Such probability x may be aconfiguration aspect of the concerned MAC entity.

In another example approach, the probability x may vary with time. Suchtime may be a TTI or may be a configured power allocation period. Forexample, the probability x may be updated in any TTI for which the WTRUperforms at least one transmission such that its value may be decreasedif the transmission is associated to the concerned MAC entity andpossibly also if no prioritization function (e.g. power scaling) isapplied, or its value may be decreased otherwise.

In another example approach, such adaptation may be derived fromprevious prioritization (e.g. scaling) events applied on transmissionsperformed by the WTRU. For example, the probability x may be updated inany TTI for which the WTRU performs at least one transmission associatedto each MAC entities and where a prioritization function (e.g. powerscaling) is applied, such that its value may be increased if the WTRUhas applied power scaling to the transmission power (or an equivalentfunction e.g. selective transmission) of at least one transmissionassociated to the concerned MAC entity, or decreased otherwise.

In another example approach, the value of x may be one of a discrete setof values e.g. [0.1, . . . , 0.9] with intermediate values in stepincrement of 0.1.

In another example approach, such adaptation may use a probabilityfunction associated with a state. Such state may be a priority levelassociated to the concerned MAC entity. Such state may be based on aperiod of time, such as based on a single previous TTI (or alternativelya period during which the priority was not subject to change from oneTTI to the other). Such previous TTI may include either: the TTIimmediately before the TTI for the current transmission; or the TTI ofthe previously made transmission; or the TTI in which the WTRU may atleast one transmission associated to each of the MAC entities thatcontend for power in the concerned TTI.

Such previous TTI may be a TTI in which the WTRU applied one of theprioritization functions (e.g. power scaling). For example, such TTI maybe the last TTI in which the WTRU applied power scaling to at least oneof its transmissions.

For example, the WTRU may determine the priority associated totransmissions of a first MAC entity using a Markov chain where thecurrent state associated to the concerned MAC entity is the outcomedetermined in the previous TTI for which the WTRU applied power scalingand for which the WTRU had at least one transmission for at least eachof two MAC entities. Alternatively, such period may be a configuredpower allocation period.

In some deployment scenarios, timing of transmissions associated todifferent MAC entities may differ such that some overlap may occurbetween a transmission performed in subframe n for a first MAC entityand a transmission performed in subframe n+1 for a second MAC entity. Insuch case, the total transmission power may exceed the maximum WTRUtransmit power WTRU temporarily. It may be problematic for a WTRU toscale power properly for consecutive subframes if the priority changesfrom one TTI to the other.

In one example approach, the WTRU may modify the priority associated toa MAC entity only for a TTI that immediately follows a TTI for whichpower scaling was not applied. Possibly, for stateful functions asdescribed above, the WTRU may consider only such TTIs; in other words,the WTRU may only keep track of the outcome of the function used todetermine priority when such priority may be changed. Alternatively, theWTRU may consider any TTI in which power scaling is applied when itmaintains state; in other words, the WTRU may keep track of the assignedpriority when applying power scaling for the function used to determinepriority.

In a case where two different MAC entities are each configured with adifferent TTI duration (e.g. such as where each MAC entity is configuredusing a different Radio Access Technology), similar methods may be usedfor the time for which the WTRU has overlapping transmissions or for aconfigured power allocation period.

In an example approach, the WTRU may first allocate transmission powerto any transmission that contains UCI (including PUCCH and/or PUSCH withUCI) and, for remaining transmissions it may use any of the abovefunctions to determine the identity of the MAC entity for which theassociated transmissions may then be allocated any remaining power; ifany power remains, it may finally be allocated to the MAC entity thatlost contention.

In another example approach, the WTRU may first allocate transmissionpower to any transmission that contains UCI (including PUCCH and/orPUSCH with UCI). If total available power is insufficient, aprioritization function may be applied (e.g. power scaling) at this stepe.g. PMAC first then SMAC. For remaining transmissions it may use any ofthe above functions to determine the identity of the MAC entity forwhich the associated transmissions may then be allocated any remainingpower; if any power remains, it may finally be allocated to the MACentity that lost contention.

In another example approach, the WTRU may first allocate transmissionpower to any transmission associated to the PCell of the PMAC and, forremaining transmissions it may use any of the above functions todetermine the identity of the MAC entity for which the associatedtransmissions may then be allocated any remaining power; if any powerremains, it may finally be allocated to the MAC entity that lostcontention.

In another example approach, the WTRU may first allocate transmissionpower to any transmission associated to the PCell of the PMAC and to anytransmission associated to a special cell of the SMAC. If totalavailable power is insufficient, a prioritization function may beapplied (e.g. power scaling) at this step e.g. PMAC first then SMAC. Forremaining transmissions it may use any of the above functions todetermine the identity of the MAC entity for which the associatedtransmissions may then be allocated any remaining power; if any powerremains, it may finally be allocated to the MAC entity that lostcontention.

FIG. 9 is a flowchart 900 illustrating an example application ofadaptive prioritization functions. On a condition 910 that the WTRU isconfigured for operation in a dual connectivity mode the WTRU maydetermine in a step 930 whether the maximum amount of power available tothe WTRU for uplink transmissions in a time interval is sufficient forall UCI uplink transmissions during the time interval without powerscaling. If so, the WTRU may allocate power to UCI uplink transmissionsper MAC entity without prioritization in step 940 (for example, by notscaling the power for these transmissions). Otherwise, the WTRU mayallocate power to UCI uplink transmissions in step 950 during thetransmission using a prioritization function (for example, by scalingthe allocated transmission power for each of the transmissions, possiblyaccording to priority).

The WTRU may also determine in step 960 whether, after allocating powerto UCI uplink transmissions, any excess power is available to allocateto any non-UCI transmissions (i.e., whether the power allocated to UCItransmissions in step 940 or 950 is less than the maximum amount ofpower available to the WTRU for all uplink transmissions in the timeinterval). If power is not available for non-UCI transmissions, the WTRUmay, in step 965, transmit the transmissions as allocated. If power isavailable for non-UCI transmissions, the WTRU may determine in step 970whether the remaining power is sufficient for all non-UCI transmissionsscheduled during the time interval to be transmitted without scaling. Ifso, the WTRU may allocate power to non-UCI uplink transmissions in step980 by not scaling the power for these transmissions. Otherwise, theWTRU may allocate power to non-UCI uplink transmissions in step 990using a prioritization function (for example, by scaling the allocatedtransmission power for each of the transmissions, possibly according topriority).

FIG. 10 shows a flow chart 1000 which illustrates an exampleprioritization of transmissions according to CG type. In the example ofFIG. 10, transmissions to a master cell group (MCG) are prioritizedabove transmissions to other types of cell group, such as secondary cellgroups (SCG), although in principle another priority order may beimplemented. The procedure illustrated in flow chart 1000 may be used toprioritize transmissions when allocating remaining power such as in step1260 of FIG. 12, for example.

In step 1005 priority is set to q=0 to begin prioritization at thegreatest priority level. On a condition 1010 that CG1 comprises an MCG,the WTRU allocates remaining power in step 1015 to each as yetunallocated uplink transmission having priority q which is scheduled fortransmission using the uplink resources of CG1 in a time interval. Instep 1020 the WTRU may determine whether any unallocated remaining poweris available and if not, the procedure ends. If unallocated remainingpower is available, the WTRU may allocate the available power in step1025 to each as yet unallocated uplink transmission having priority qwhich is scheduled for transmission using the uplink resources of CG2.In step 1030 the WTRU may determine whether any unallocated remainingpower is available and if not, the procedure ends. If unallocatedremaining power is available, the WTRU may determine in step 1035whether any uplink transmissions of priority level q′>q are scheduledfor the time interval (i.e. whether any transmissions are scheduled foruplink during the time interval having lesser priority than q). If not,the procedure ends. If so, the value of q may be incremented in step1040 and the procedure may return to condition 1010 in order to considerthe next priority level.

If the WTRU determines in condition 1010 that CG1 does not comprise anMCG, the WTRU may determine in step 1045 whether CG2 comprises an MCG.If CG2 comprises an MCG, the WTRU may allocate remaining power in step1050 to each as yet unallocated uplink transmission having priority qwhich is scheduled for transmission using the uplink resources of CG2 inthe time interval. In step 1055 the WTRU may determine whether anyunallocated remaining power is available, and if not, the procedureends. If unallocated remaining power is available, the WTRU may allocatethe available remaining power in step 1060 to each as yet unallocateduplink transmission having priority q which is scheduled fortransmission using the uplink resources of CG1. In step 1065 the WTRUmay determine whether any unallocated remaining power is available andif not, the procedure ends. If unallocated remaining power is available,the WTRU may determine in step 1035 whether any uplink transmissions ofpriority level q′>q are scheduled for the time interval (i.e. whetherany transmissions are scheduled for uplink during the time intervalhaving lesser priority than q). If not, the procedure ends. If so, thevalue of q is incremented in step 1040 and the procedure may return tocondition 1010 in order to consider the next priority level.

If the WTRU determines in step 1045 that CG2 does not comprise an MCG,then the WTRU in step 1070 may allocate any remaining power to each asyet unallocated uplink transmission having priority q which is scheduledfor transmission using the uplink resources of either CG1 or CG2 in thetime interval. In step 1075 the WTRU may determine whether there is anyremaining unallocated power for uplink transmissions in the timeinterval and if not, the procedure ends. If so, the WTRU may determinein step 1035 whether any uplink transmissions of priority level q′>q arescheduled for the time interval (i.e. whether any transmissions arescheduled for uplink during the time interval having lesser prioritythan q). If not, the procedure ends. If so, the value of q isincremented in step 1040 and the procedure may return to condition 1010in order to consider the next priority level.

Further methods for adaptive prioritization are described herein.

Similarly as for approaches described above, the WTRU may maintain othertype(s) of state to determine how to change the priority associated to agiven MAC entity.

For example, the WTRU may maintain a configured power allocation periodthat it may use to vary, from one period to another, the priority ofdifferent transmissions and/or the priority associated to different MACentities.

For example, the WTRU may maintain some state of the amount of power ithas scaled for each MAC entity, such that a specific ratio may beenforced. Possibly, such state may be maintained using a moving window.Such ratio and/or such window may be configurable aspect(s) of theWTRU's configuration.

One possible approach is to implement some form of fairness and/or meansto avoid starvation for bearers associated with a given MAC entity usingmethods that can change the scaling rate applied to each MAC entityaccording to the principle where “a (possible unequal) share of thepenalty due to the prioritization function (e.g. power scaling) isapplied to each MAC entity”. In an example, for every TTI that lead tothe need to scale the power (a scaling event), a power scaling ratio foreach MAC instance may be used similar to the above.

In one example approach, such state may be a ratio of the total scalingto be applied to different transmissions. The ratio of the total scalingapplied to one or more transmissions may be changed dynamically.

In one example approach, such state may be based on one or moremetric(s) that each describes one aspect of previous transmissions. Suchstate may be averaged over time using a (possibly configured) duration.Such duration may be useful to determine the reactiveness of a MACentity to different scheduling or transmission events as well as to makeit more predictable. How well a guaranteed “serving level” is met may betracked dynamically.

The prioritization may be a function of a metric. Such metric mayinclude accumulated quantities such as output power, number oftransmitted L1 bits, number of L1 transmissions, number of TBstransmitted, number of grants for initial transmissions, the sum of sizeof the transmitted TBs, the number of PRBs used of transmissions, thenumber of L2 bits transmitted, accumulated power scaling applied (or thecorresponding penalty) or the like. State may be expressed as aremaining amount of such quantities to be allowed or served for thegiven duration.

Such state may be specific to each MAC instance, possibly to thegranularity of the type of transmissions. Such metric(s) may bemaintained per MAC entities. Additional state may also be maintained pertype of transmissions e.g. for PUSCH. Additional state may also bemaintained by period of time e.g. for a power allocation period.Possibly, such metric may be maintained per configured (and activated)serving cell. In the following discussion, metrics per MAC entity areused for exemplary purposes.

Such metrics may be tied directly to or related to the Logical ChannelPrioritization (LCP) state for each MAC instance. Such metric may berelated to the state of the MAC LCP function. For example, one metricmay be how well configured logical channel(s) (LCH(s)) (or logicalchannel group(s) LCG(s)) are satisfied for the concerned MAC entity interms of QoS. For example, this may be based on the sum of the Bj statefor all LCHs of the concerned MAC entities. In this case, the WTRU mayfirst allocate power to transmissions associated to the MAC entity withthe highest sum (i.e. the one with the most outstanding amount of datato transmit to meet QoS requirements). Alternatively, the WTRU may firstallocate power to transmissions associated to the MAC entity for whichsuch sum is considered only for LCHs associated to at least a minimumpriority level. For example, the WTRU may consider only LCHs associatedto the highest LCG for each MAC entity.

One example implementation may involve Per-CG Minimum Guaranteed Powerand Remaining Power. The WTRU may have a rate control function for theallocation of uplink power. Possibly, such power prioritization function(PPF) may be used only when the WTRU determines that the total requiredamount of transmit power exceeds the maximum power allowed for the WTRUin a given time instant.

The WTRU may use such PPF function to allocate a prioritization rate forthe usage of available power (a prioritizedMetricRate) to each MACentity. For the purpose of example, in the following discussion themetric used will be output power (a prioritizedPowerRate or PPR) e.g.dBm per MAC entity (or per associated physical layer).

Methods for adaptive prioritization may be configurable per MAC/PHYcombination. L3/RRC may be used to control the allocation of power foreach MAC entity for situations where power scaling may be required byconfiguration. Such configuration may include a priority for each MACentity and a value for the PPR (the rate at which the WTRU allocatesthat total available power). For example, the PPR may correspond to theminimum guaranteed power for the associated CG.

FIG. 11 is a flowchart 1100 illustrating an example configuration of aWTRU for uplink transmissions scheduled to occur during a given timeinterval. In step 1110, the WTRU is configured with a first minimumguaranteed power for uplink transmissions using uplink resources of afirst cell group (CG1) scheduled for the time interval. In 1120, theWTRU is configured with a second minimum guaranteed power for uplinktransmissions using uplink resources of a second cell group (CG2)scheduled for the time interval. In step 1130, the WTRU is configuredwith a value for remaining power, which may be equal to a totalavailable power for uplink transmissions in the time interval less thetotal of the first and second minimum guaranteed powers.

It is noted that in some implementations, the configuration of the WTRUmay be considered for uplink transmissions corresponding to first andsecond MAC entities or uplink transmissions to first and second eNBsrather than as uplink transmissions using the uplink resources of CG1and CG2.

FIG. 12 is a flowchart 1200 illustrating an example of power scaling. Instep 1210, the WTRU is configured with a first minimum guaranteed powerfor uplink transmissions scheduled for the time interval using theuplink resources of a first cell group (CG1). In 1220, the WTRU isconfigured with a second minimum guaranteed power for uplinktransmissions scheduled for the time interval using the uplink resourcesof a second cell group (CG2). In step 1230, power is allocated foruplink transmissions using the uplink resources of CG1 scheduled for thetime interval up to the first minimum guaranteed power. In step 1240,power is allocated for uplink transmissions using the uplink resourcesof CG2 scheduled for the time interval up to the second minimumguaranteed power. In step 1250, the WTRU may determine whether there isany remaining power to allocate for uplink transmissions from the WTRUin the time interval (i.e., whether the total available power for uplinktransmissions in the time interval less the total of the first andsecond minimum guaranteed powers is greater than zero). If so, theremaining power is allocated to uplink transmissions in step 1260according to one of various methods described herein.

FIG. 13 is a flowchart 1300 illustrating another example of powerscaling. In step 1310, the WTRU is configured with a first minimumguaranteed power for uplink transmissions scheduled for the timeinterval using the uplink resources of a first cell group (CG1). In1320, the WTRU is configured with a second minimum guaranteed power foruplink transmissions scheduled for the time interval using the uplinkresources of a second cell group (CG2). In step 1330, power is reservedfor uplink transmissions using the uplink resources of CG1 scheduled forthe time interval up to the first minimum guaranteed power. In step1340, power is reserved for uplink transmissions using the uplinkresources of CG2 scheduled for the time interval up to the secondminimum guaranteed power. In step 1350, the WTRU may determine whetherthere is any remaining power to allocate for uplink transmissions fromthe WTRU in the time interval (i.e., whether the total available powerfor uplink transmissions in the time interval less the total of thefirst and second reserved powers is greater than zero). If so, theremaining power is allocated to uplink transmissions in step 1360according to one of various methods described herein.

It is noted that in some implementations, the configuration of the WTRUmay be conceptualized as for uplink transmissions corresponding to afirst MAC entity and to a second MAC entity or transmitted to a firsteNB and to a second eNB, rather than as using the uplink resources ofCG1 and CG2.

In one example approach, the WTRU may use the PPF function to ensurethat it serves scheduling instructions and expected transmissionsaccording to the following:

The WTRU may first allocate transmission power to transmissionsassociated to a first MAC entity up to the concerned MAC entity's PPR(e.g. up to its minimum guaranteed power), possibly in decreasingpriority order if such is associated to different transmission and/ortransmission types and if power scaling is required for the first MACentity (i.e. the allocated transmit power required for all transmissionsof the concerned MAC entity exceeds the available PPR for the MACentity);

The WTRU may then allocate remaining transmission power (if any) totransmissions associated to a second MAC entity up to the concerned MACentity's PPR (e.g. up to its minimum guaranteed power), possibly indecreasing priority order if such is associated to differenttransmission and/or transmission types and if power scaling is requiredfor the concerned MAC entity (i.e. the allocated transmit power requiredfor all transmissions of the first MAC entity exceeds the available PPRfor the MAC entity);

For the above, if any power remains after a first round of powerallocation to each applicable MAC entity, the WTRU may allocateremaining power in decreasing priority order, either:

-   -   a. In decreasing priority of the concerned MAC entities; or    -   b. In decreasing priority associated to different transmission        and/or transmission types across all concerned MAC entities; or    -   c. Using a combination of both in the same order (i.e. first for        transmissions of the first MAC entity, then for transmissions of        the second MAC entity); and,

For the above, where the first MAC entity is assigned a higher prioritythat a second MAC entity, the WTRU may allocate remaining poweraccording to any other method described herein.

For the above, where transmissions associated to a MAC entity may beassigned different relative priorities, the WTRU may allocate remainingpower according to any other method described herein.

In some cases, configuration of the minimum guaranteed power/PPR may beused for adaptive prioritization. The above realization may work withany levels configured with a PPR (or minimum guaranteed power) forexample, where the sum of the configured PPR is less than the maximumavailable WTRU power. The flexibility of such realization may be furtherillustrated using a number of configuration aspects and/orcombinations/settings of values as discussed herein.

In some cases, minimum guaranteed power may be “infinite” for oneCG—Absolute Priority. Possibly, a specific PPR value may be defined toindicate absolute priority for the associated MAC instance, e.g.“infinity”. In this case, the WTRU first allocates as much of theavailable transmit power to transmissions of the concerned MAC entityand possibly in decreasing priority order if such is applicable and ifpower scaling is required for this step.

In some cases, minimum guaranteed power for a CG may equal zero (0)—CGonly participates in the Flat Scaling part. Possibly, a specific PPRvalue may be defined to indicate that transmissions associated to a MACentity may only be allocated power that remains once the WTRU hasdistributed non-zero guaranteed power to at least one applicable MACentity.

In some cases, the sum of minimum guaranteed power for each CG may equalzero (0). In particular, the WTRU may be configured with minimumguaranteed power equal to zero for all applicable MAC entities. In thiscase, the WTRU allocates any available power as “remaining power.”

In such cases, if the WTRU allocates remaining power in (as discussedabove) decreasing priority of the MAC entities, this may becomeequivalent to a configuration where a MAC entity may have absolutepriority; for example, this may be used in combination with othermethods described herein such as methods that dynamically assignpriorities.

In such cases, if the WTRU allocates remaining power in (as discussedabove) decreasing priority of transmissions across all applicable MACentities, this may become similar to the WTRU performing flat scalingusing applicable priority rules applied between transmissions across allof the WTRU's transmissions.

In such cases, if the WTRU allocates remaining power using a combinationof prioritization methods for MAC entities and across transmissions (asdiscussed above) this may become similar to the WTRU assigning absolutepriority to the MAC instance with the transmission that has absolutehighest priority based on applicable priority rules applied betweentransmissions across all of the WTRU's transmissions.

In some cases the sum of minimum guaranteed power for all CGs may equal100% of maximum WTRU available power. In such cases, the WTRU may beconfigured such that the sum of the configured PPR values for allapplicable MAC entities exceeds the maximum amount of power available tothe WTRU. In this case, the WTRU may allocate power using prioritizationmethods as described in other sections herein and the PPR may behave asa maximum power for transmissions associated to a MAC entity when theWTRU is power-limited.

An example of power allocation formulation is discussed further herein.Where power is allocated according to the above principles, the maximumpower S_(n) that is available to transmissions associated to a given MACentity CG1 and priority level n may correspond to the power notallocated to (1) transmissions of higher priority and (2) transmissionsof lower priority of the other MAC entity for which guaranteed power isavailable. This may be represented as follows:

S _(n) =P _(CMAX) =P _(u,n) −P _(q,n)−min(P _(av,gua) ,P′_(q,n)  Equation (1)

where P_(CMAX) is the configured maximum power of the WTRU, P_(u,n) isthe power allocated to transmissions of higher priority of the same MACentity (CG1), P_(q,n) is the power allocated to transmissions of higherpriority of the other MAC entity CG2, P′_(q,n) is the power required fortransmissions of lower priority of the other MAC entity CG2, andP_(av,gua) is the portion of the guaranteed power of the other MACentity that may still be available for transmissions of lower priorityof the other MAC entity CG2. This portion may be represented as:

P _(av,gua)=max(0,P _(CMAX) ·R _(CG2) ^(g) −P _(q,n))  Equation (2)

where R^(g) _(CG2) is the guaranteed power of the other MAC entityexpressed as a ratio of P_(CMAX).

The WTRU may be configured such that the sum of the configured PPRvalues for all applicable MAC entities corresponds to the maximum amountof power available to the WTRU. In this case, the WTRU may allocatepower to each CG up to their minimum guaranteed; if there is remainingpower following this step, the WTRU may allocate it to transmissions ofa MAC entity that requires more than the minimum guaranteed such thatsome form of semi-static split with sharing may be realized for powerallocation. More specifically, where the WTRU is power-limited fortransmissions of both MAC entities then this may be equivalent to asemi-static split; where the WTRU is power-limited for transmissions inonly one MAC entity then some sharing of any unused power may beperformed between MAC entities and if insufficient, the WTRU may performa prioritization function (e.g. power scaling) across transmissionsassociated to the concerned MAC entity only.

The WTRU may be configured with a maximum power per serving cellP_(CMAX,c)(i) in subframe i for the purpose of determining the power oftransmission(s) for serving cell c, before scaling. In some approaches,the WTRU may also be configured with a maximum power per MAC instance,P_(CMAXM,m)(i), which may be used in the determination of the finaltransmission powers (after scaling). In some solutions, the WTRU mayalso be configured to use a guaranteed available power per MAC instanceP^(g) _(m)(i). The above parameters may also be used for the calculationof power headrooms or of additional types of power headroom.

In some approaches, one or more of the above power limits, or guaranteedavailable power, for a first MAC instance, or cells of a first MACinstance, may be reduced in a subframe when the WTRU determines that allbearers associated to this first MAC instance meet or exceed a set of atleast one QoS criteria, while at least one bearer associated to a secondMAC instance do not meet at least one QoS criterion. Such adjustment mayprevent, for instance, a scenario where starvation of bearers of alower-priority MAC instance occurs while bearers exceed their QoS in ahigher-priority MAC instance.

The amount of reduction may be configured by higher layers. Forinstance, higher layers may configure an adjustment of 1 dB or 3 dB toapply to either or all of the P_(CMAX,c)(i) of each serving cell c andP_(CMAXM,m)(i) or P^(g) _(m)(i) of the MAC instance to which thereduction applies.

In an example approach, the determination of whether a reduction shouldapply or not may be performed periodically (e.g. once per RTT, one perinteger multiple of a radio frame), possibly as frequently as on asubframe basis. The reduction may remain in force until the nextdetermination. In another approach extending the previous one, thereduction may apply only in a subframe during which the WTRU performs atleast one transmission for each concerned MAC entity and/or powerscaling is required. In another approach, such determination may beapplicable and/or performed only for a period (or for a subframe) forwhich the WTRU is performing at least one uplink transmission andpossibly, only if there is at least one such transmission for eachconcerned MAC entity.

In one approach, the reduction may be applied to a first MAC instance ifall of the bearers of this MAC instance are “satisfied”, while at leastone bearer of a second MAC instance is “not satisfied”.

A number of criteria may be used for determining if a bearer issatisfied or not, including at least one of:

For a logical channel with finite prioritized bit rate, the bearer maybe satisfied if the bucket size of the corresponding logical channeldoes not exceed a threshold, in a reference subframe. The threshold maybe, for instance, the product of the prioritized bit rate and of thebucket size duration.

For a logical channel with infinite prioritized bit rate, the bearer maybe satisfied if there is no data available for transmission, in areference subframe. Possibly, this may also be applicable for a logicalchannel with finite prioritized bit rate.

The reference subframe may be the subframe for which a power limitreduction would apply, or possibly a previous subframe (e.g. 1 subframeearlier).

In another approach, the reduction may be applied to a first MACinstance if the logical channel prioritization procedure for this MACinstance reaches the “satisfaction point” in a reference subframe, whilethe logical channel prioritization procedure does not reach the“satisfaction point” in a second MAC instance in the reference subframe.The logical channel prioritization procedure is said to reach the“satisfaction point” if it reaches the point where all variables Bj arenon-positive (i.e. equal or less than zero) in the reference subframe.Possibly, the satisfaction pint is also reached if resources are stillremaining in at least one transport block in the reference subframe.

In another approach, the reduction may be applied to a first MAC entityas a function of the state of the HARQ processes. For example, a WTRUmay be configured with a HARQ operating point value. If the WTRUdetermines that it operates below such HARQ operating point for a MACentity, it may apply the power limit reduction for the concerned MACentity. The WTRU may determine its HARQ operating state using e.g. amoving average of the number of transmissions for each processesassociated to the concerned MAC entity. In one approach, the WTRU mayconsider all such HARQ processes. In another approach, the WTRU mayconsider only ongoing HARQ processes e.g. HARQ processes for which thelast received feedback is NACK.

In another approach, the reduction may be applied to a first MAC entityas a function of the rate of new HARQ processes e.g. at the rate atwhich it determines that NDI has been toggled for a given HARQ process.For example, a WTRU may be configured with a new transmission rate (NTR)value. If the WTRU determines that it operates above such NTR value fora MAC entity, it may apply the power limit reduction for the concernedMAC entity (e.g. to implicitly force fairness to a too greedyscheduler). The WTRU may determine its NTR value using e.g. a movingaverage of the number of HARQ processes for which it has considered theNDI bits to have been toggled for processes associated to the concernedMAC entity. The corresponding period may be set to RTT (i.e. 8 ms forLTE)*the maximum number of HARQ transmissions.

One approach for realizing a prioritization function is by performingscaling of transmission power. The following discussion describesapproaches for determining the transmission powers of different types oftransmissions for a WTRU operating in dual connectivity, taking intoaccount for instance the following aspects:

-   -   The possibility of simultaneous transmission of PUCCH or UCI in        multiple serving cells (for multiple MAC instances);    -   The possibility of a multiplicity of priority levels between        transmissions, as well as sub-priority levels;    -   The possibility of multiple limits for the total power over        subsets of transmissions; and    -   The possibility of non-alignment between subframe boundaries of        different subset of transmissions, or different MAC instances.

In a subframe i, a WTRU may be configured with a maximum power perserving cell P_(CMAX,e)(i), and a total configured maximum output powerP_(CMAX)(i).

In addition, the WTRU may be configured with a maximum output power perMAC entity (or per layer or per eNB), P_(CMAXM,m)(i). In this case, thesum of the powers of all transmissions pertaining to this MAC entitycannot exceed P_(CMAXM,m)(i) in subframe i. In a dual connectivitysystem, m can take the values 0 or 1. Without loss of generality, m=0may refer to a Primary MAC instance and m=1 may refer to a Secondary MACinstance. In some solutions, the maximum output power per MAC entity maycorrespond to a Prioritized Power Rate (PPR) for this MAC entity.

The WTRU may perform one or more transmissions in a subframe for one ormore physical channels (e.g. PUCCH, PUSCH, PRACH) or signal (SRS)pertaining to one or more MAC instances. For each type of transmissiont, the WTRU may first calculate a transmission power in subframe i,P_(t)(i), that does not take into account any power limitation overmultiple transmissions such as P_(CMAX)(i) or P_(CMAXM,m)(i). Suchtransmission power value is referred to as the “pre-scaled” power in thefollowing. The calculation of the pre-scaled power P_(t)(i) for atransmission t may be performed based on a path loss reference,closed-loop adjustments, grants or other parameters associated to theMAC instance controlling t, according to existing rules specific to thetype of transmission (PUCCH, PUSCH, SRS, PRACH).

In some solutions, some or all pre-scaled powers Pt(i) may have beenobtained as the output of a previous scaling procedure. For instance,for at least one MAC instance m, the subset of transmissions Pt(i)pertaining to MAC instance m may itself have been calculated from anearlier step of scaling within this subset of transmissions and usingP_(CMAXM,m)(i), or some other value as maximum power. More generally,the pre-scaled power P_(t)(i) in the scaling procedure set forth in thefollowing may correspond to an amount of desired power, (or, in certainsolutions, an amount of desired portion of power), for a transmission t,where a limitation exists for the total desired power or total desiredportion of power over transmissions.

For various approaches described herein, it should be understood thateven though the transmission powers calculations are shown on a subframebasis, the WTRU may determine different transmission powers between twoslots of the same subframe or between the last SC-FDMA symbol and otherSC-FDMA symbols, based for instance on possible variations of themaximum power per serving cell P_(CMAX,c)(i) within a subframe, or basedon a different power requirement in the last symbol due to transmissionof SRS. In other words, the calculations shown below may be applied byportions of subframes, e.g. on a per-slot basis, or separately betweenthe last SC-FDMA symbol containing SRS and the earlier SC-FDMA symbols.

Scaling with single maximum total level and multiple priority levels(single scaling): Where the WTRU operates in dual connectivity, atransmission t may be associated to a priority level q for at least thepurpose of scaling. There may be one, two or more priority levels Q.There may be zero, one or more transmissions t associated to a certainpriority level q. The priority level (or order) may be obtained usingany of the approaches described in earlier sections, such as dynamicmethods or semi-static methods.

The sum of pre-scaled transmission powers for a set of transmissions Tmay exceed a maximum total P_(MAX)(i) applicable to this set oftransmissions in subframe i. For instance, the set of transmissions Tmay correspond to all transmissions in subframe (i), or alltransmissions for a subset of physical channels (e.g. PUSCH and PUSCHtransmissions only) in which case the maximum total P_(MAX)(i) maycorrespond to P_(CMAX)(i). In another example, the set of transmissionsT may correspond to all transmissions pertaining to a specific MACinstance, in which case the maximum total P_(MAX)(i) may correspond toP_(CMAXM,m)(i). When this occurs, the final transmission power P′_(t)(i)of at least one transmission t may be scaled down by a factor w_(t)(i)ranging from 0 to 1, such that P′_(t)(i)=w_(t)(i) P_(t)(i) in linearunits. In the description of solutions involving scaling, the WTRU maybe said to be performing a scaling procedure over a set of pre-scaledpowers using a maximum total power level, and the outcome (or output) ofthis procedure is a set of final transmission powers. In the followingparagraphs describing how a scaling procedure may be performed, the setof pre-scaled powers is denoted as P_(t)(i) and the set of finaltransmission powers is denoted as P′_(t)(i), but other notations may beused in the description of solutions involving multiple applications ofa scaling procedure.

In an example approach, scaling may be applied such that the scalingfactor is as high as possible for higher priority transmissions. Whenthe scaling factor is less than 1 for a transmission of priority q, anytransmission of lower priority (e.g. any transmission with q′>q, where alarger value of q means lower priority) is scaled down to zero, i.e. notransmission takes place for the lower priority transmissions. Inaddition, no scaling is allowed to take place for any transmission ofhigher priority, i.e. the scaling factor is 1 for any transmission withq′<q.

With this approach, the procedure to determine the scaling factors foreach transmission may be as follows. Start with the set of transmissionsTo associated to the highest priority level q=0 and determine if the sumof pre-scaled transmission powers exceeds the maximum, i.e.:

ΣtεT ₀ P _(t)(i)>P _(MAX)(i)  Equation (3)

In case the sum exceeds the maximum, the scaling factors may be setaccording to the following:

w _(t)(i)=0∀tεT _(q) ,q>0  Equation (4)

Σ_(tεT) ₀ w _(t)(i)P _(t)(i)=P _(MAX)(i)  Equation (5)

In case the sum does not exceed the maximum, the scaling factors for thehighest priority transmissions T₀ may be set to 1 (i.e., no scaling isapplied) and scaling may be applied to transmissions of lower priority.This can be determined in the following way for transmissions ofpriority level(s) q>0:

Determine if scaling is to be applied to transmissions of priority q bysumming the powers of all transmissions of equal or higher priority andcomparing to the maximum:

Σ_(tεT) _(q′) ,_(q′≦q) P _(t)(i)>P _(MAX)(i)  Equation (6)

In case the condition is satisfied, apply scaling to transmissions ofpriority q (and all lower priority transmissions) by setting scalingfactors in the following way (and the procedure ends):

w _(t)(i)=0 ∀tεT _(q′) ,q′>q  Equation (7)

Σ_(tεT) _(q) w _(t)(i)P _(t)(i)=P _(MAX) ^(q)(i)  Equation (8)

Where P_(MAX) ^(q)(i) is defined as the available total power oftransmissions of priority q:

P _(MAX) ^(q)(i)≡P _(MAX)(i)−Σ_(tεT) _(q′) ,_(q′<q) P _(t)(i)  Equation(9)

In case the condition is not satisfied, set w_(t)(i)=1 for alltransmissions t of priority q, and go back to step (a) for transmissionsof priority q+1. If no such transmission exists then no scaling needs tobe applied.

In the above, where scaling is to be applied on more than onetransmission of the same priority multiple approaches are possible forthe setting of scaling of individual transmissions, as described in thefollowing.

In one approach, the same scaling value is applied to all transmissionsof the same priority. This means that:

w _(t)(i)=w _(q)(i)∀tεT _(q)  Equation (10)

This implies that the value of w_(t)(i) is set according to:

$\begin{matrix}{{{w_{t}(i)} = {{w_{q}(i)} = \frac{P_{MAX}^{\; q}(i)}{\sum\limits_{t \in T_{q}}\; {P_{t}(i)}}}},{\forall{t \in T_{q}}}} & {{Equation}\mspace{14mu} (11)}\end{matrix}$

FIG. 14 is a flowchart 1400 illustrating an example of power scaling. Instep 1410, the WTRU may first calculate a pre-scaled power for eachuplink transmission scheduled in the time interval (Pt(i)). In step1420, a priority level q under consideration is set to zero, which inthis example represents the greatest priority level. It is noted thatthe numbering of the priority levels is illustrative, and any othersuitable representation of priority levels may be used.

In step 1430, the WTRU may determine whether the sum of prescaled powerfor all uplink transmissions of priority q scheduled in the timeinterval is greater than the maximum amount of power available for alluplink transmissions at that priority level. For instance, at q=0, thegreatest priority level, the maximum amount of power available is thetotal maximum amount of power available for all uplink transmissions,while at a lesser priority level (i.e. q>0) the maximum amount of poweravailable is the total maximum amount of power available for all uplinktransmissions less the amount of power already allocated totransmissions having greater priority.

If the WTRU determines in step 1430 that the sum of prescaled power forall uplink transmissions of priority q scheduled in the time interval isgreater than the maximum amount of power available at that prioritylevel, the power for each transmission at priority q is scaled in step1440. Here, each transmission at priority q may be scaled (e.g. using aweighting factor wt(i)) such that the total scaled power required forall transmissions at priority q is equal to the maximum amount of poweravailable for all uplink transmissions at priority q. In step 1450, zeropower is allocated to transmissions (e.g. by setting the correspondingweighting factor to zero) at priority levels q′>q (i.e. lower inimportance than q), and the procedure ends.

If on the other hand the WTRU determines in step 1430 that the sum ofprescaled power for all uplink transmissions of priority q which arescheduled in the time interval is less than the maximum amount of poweravailable for uplink transmissions at that priority level, the fullpre-scaled power may be allocated to each uplink transmission atpriority q in step 1460. For example, a weighting factor of 1 may beapplied to the pre-scaled power of each transmission at priority q.

In step 1470 the WTRU may determine whether any uplink transmissions ofpriority level q′>q are scheduled for the time interval (i.e. whetherany transmissions are scheduled for uplink during the time intervalhaving lesser priority than q). If not, the procedure ends. If so, thevalue of q may be incremented in step 1480 and the procedure returns tostep 1430 in order to consider the next priority level.

It is noted that in some implementations, the uplink transmissions maybe considered as corresponding to different MAC entities, or transmittedto different eNBs rather than as performed using the uplink resources ofdifferent CGs.

In another approach, the scaling values within transmissions associatedto a priority level q may be determined according to a sub-prioritylevel S_(q). In this case, the scaling values of transmissions ofpriority q may be set to different values depending on theirsub-priority levels. The procedure for determining the set of scalingvalues for transmissions of priority q may be similar to the aboveprocedure, but with the maximum total power set to P_(MAX) ^(q)(i)instead of P_(MAX)(i) and the sub-priority levels S_(q) used in place ofpriority levels q.

In some approaches, some types of transmissions may be eithertransmitted at their pre-scaled power or not transmitted at all, i.e.dropped. This may be the case, for instance, for transmissions such asSRS or transmissions including HARQ A/N for which a transmission at ascaled power could potentially result in worse performance than droppingthe transmission, or for transmissions for which the required scalingweight w_(t)(i) is so low that successful reception is determined to bevery unlikely. Such transmissions may be referred to as “non-scalable”transmissions. The scaling procedure in such solutions may be generallythe same as previously described, with the following modification. Whereit is determined that scaling (with w_(t)(i) less than 1) would need tobe applied to a non-scalable transmission, the scaling procedure may bestopped and a new scaling procedure may be initiated with a set oftransmissions not including this non-scalable transmission. This may bedone multiple times until there are no remaining non-scalabletransmissions on which scaling would need to be applied. Alternatively,instead of stopping the scaling procedure, the scaling factor of thenon-scalable transmission may be set to 0 and the remaining availablepower of other transmissions of equal or lower priority may bere-calculated for the purpose of determining scaling factors of theseother transmissions.

In some solutions, the scaling weights may be determined to be such thatthe sum of scaled transmission powers over transmission of a givenpriority level is less than the maximum available, i.e.:

Σ_(tεT) _(q) w _(t)(i)P _(t)(i)<P _(MAX) ^(q)(i)  Equation (12)

Setting weights satisfying the above condition may be referred to as“power under-allocation” at priority level q in the following. Powerunder-allocation at a priority level q may be performed, for instance,when there is at least one transmission to that is “non-scalable” asdescribed in the above, at least if the scaling weights would be set toidentical non-zero values for all transmissions of this priority level,i.e. to:

$\begin{matrix}\frac{P_{MAX}^{\; q}(i)}{\sum\limits_{t \in T_{q}}\; {P_{t}(i)}} & {{Equation}\mspace{14mu} (13)}\end{matrix}$

Such transmission to may be dropped (i.e. scaling weight set to 0) andthe scaling weights for remaining transmissions may be set to:

$\begin{matrix}{{{w_{t}(i)} = {{w_{q}(i)} = {\min\left( {\frac{P_{MAX}^{\; q}(i)}{\sum\limits_{{t \in T_{q}},{t \neq t_{0}}}{P_{t}(i)}},1} \right)}}},{\forall{t \in T_{q}}},{t \neq t_{0}}} & {{Equation}\mspace{14mu} (14)}\end{matrix}$

When w_(t)(i)=1 for all transmissions other than to, the powerreallocated from t₀ to other transmissions may be sufficient to preventscaling for these transmissions, such that power under-allocation mayoccur.

In some solutions, power under-allocation at a priority level q may beperformed such that the unused power:

P _(MAX) ^(q)(i)−Σ_(tεT) _(q) w _(t)(i)P _(t)(i)  Equation (15)

is minimized. Alternatively, power under-allocation may be performedsuch that the number of transmissions for which the scaling weight iszero (dropped) is minimized. Alternatively, power under-allocation maybe performed such that for a transmission scaled down to zero, notscaling down this transmission to zero would not result in powerunder-allocation.

In some solutions, power under-allocation at a priority level q may beperformed only in case there is no transmission of lower priority. Insome of such solutions, when at least one transmission is of lowerpriority in subframe i, all transmissions of priority level q may beconsidered scalable.

In some solutions, power under-allocation at a priority level q may beallowed even if there is at least one transmission of lower priority.However in some such solutions, when power under-allocation occurs for apriority level q, no power may be allocated or re-allocated to anytransmission of lower priority, even if power would be available forthese transmissions due to under-allocation at priority level q. Forexample, if priority level q corresponds to PUSCH transmissions withoutUCI for MCG, and scaling would need to be applied to transmissions ofpriority level q, no power would be allocated to transmissions of lowerpriority such as PUSCH transmissions without UCI for SCG (possibly asidefrom any power reserved or guaranteed to SCG transmissions that maystill be available). Expressed differently, in some such solutions noremaining power would be allocated to PUSCH transmissions without UCIfor SCG.

In some solutions, where power under-allocation occurs for a prioritylevel q, the unused power:

P _(MAX) ^(q)(i)−Σ_(tεT) _(q) w _(t)(i)P _(t)(i)  Equation (16)

may be re-allocated to transmissions of a lower priority (q′>q). Suchre-allocation may be unconditional. Alternatively, whether re-allocationis performed or not may depend on at least one of the followingconditions:

-   -   a) The MAC instance or cell group to which the transmissions of        lower priority (q′) and/or higher priority (q) are associated.        For instance, reallocation may be performed if transmissions of        lower priority are associated to a cell group different than the        one for transmissions of higher priority. Alternatively,        re-allocation may be performed if transmissions of lower        priority are associated to the same cell group. In another        example, reallocation may be permitted if transmissions of lower        priority are associated to the MCG.    -   b) At least one criterion determining the priority level of q or        q′, or the relative priority of priority levels q and q′. For        instance, re-allocation may occur only if transmissions        associated to q and q′ are of the same UCI type, and/or differ        only with respect to the cell group (MCG versus SCG). For        instance, reallocation may be performed from a transmission of        the MCG containing HARQ A/N to a transmission of the SCG        containing HARQ A/N.    -   c) The type of transmission of lower priority (q′) and/or higher        priority (q). For instance, reallocation may be performed from a        PRACH transmission to another type of transmission. In another        example, re-allocation may not be performed from a PUCCH        transmission (i.e. from a priority level q, if the scaled down        transmission is PUCCH) to another transmission.

Scaling based on power sharing between MAC instances (multiple scaling):In some approaches, transmissions taking place in a subframe i may besubject to more than one limitation. For instance, the sum of the powersof all transmissions associated to a MAC instance (or cell group) m maybe configured to be limited to a value P_(CMAXM,m)(i), for each MACinstance. At the same time, the sum of the powers of all transmissions(over all MAC instances) may also be configured to be limited to a valueP_(CMAX)(i). In some solutions, the configured maximum powerP_(CMAXM,m)(i) for MAC instance m may be equal to P_(CMAX)(i), possiblyby default. The maximum power P_(CMAXM,m)(i) of one MAC instance m maybe equivalent to the difference between P_(CMAX)(i) and a guaranteedpower P^(g) _(m′)(i) configured for the other MAC instance m′, forexample, when the power requirement of the other MAC instance is notknown.

Determination of configured maximum powers in case of limitation per MACinstance: In solutions where a configured maximum power P_(CMAXM,m) isdefined for each MAC instance (or cell group), the applicable lower andupper bounds of this quantity, and well as the lower and upper bounds ofthe total configured maximum output power P_(CMAX) and of the configuredmaximum output power P_(CMAX,c) for a serving cell c, may be dependenton an assigned maximum power P_(eNB,m) determined for each MAC instance(or cell group) m. The determination of the assigned maximum powerP_(eNB,m) may be performed according to solutions described herein. Inaddition, the assigned maximum power PeNB,m may correspond to themaximum power from the WTRU power class PPowerClass (and formulas may besimplified accordingly) at least in the following cases: In a case whereno parameters are provided or defined to determine assigned maximumpowers PeNB,m; in a case where transmissions from at most one MACinstance or cell group are on-going in a given subframe (i.e. the WTRUtransmits to a single eNB), i.e. no overlap exists between transmissionsof different cell groups; or in a case where the WTRU is configured totransmit over a single cell group (or configured with a single MACinstance), e.g. following a reconfiguration procedure (RRC signaling) orfollowing MAC signaling.

In the following the notation P_(eNB,m) refers to the assigned maximumpower in logarithmic units (e.g. dBm) while p_(eNB,m) refers to theassigned maximum power in linear units.

Configured maximum power per MAC instance (cell group) P_(CMAXM,m:) Insome solutions, the configured maximum power P_(CMAXM,m) applicable to aMAC instance (or cell group) may be bounded by a lower bound P_(CMAXM)_(_) _(L,m) and an upper bound P_(CMAXM) _(_) _(H,m), such that:

P _(CMAXM) _(_) _(L,m) ≦P _(CMAXM,m) ≦P _(CMAXM) _(_) _(H,m)  Equation(17)

The upper bound P_(CMAXM) _(_) _(H,m) may be set as the minimum valuebetween a maximum WTRU power P_(PowerClass), the sum of linear powersp_(EMAX,c) over all serving cells c belonging to MAC instance (or cellgroup) m, and the assigned maximum power P_(eNB,m), where each term isconverted to logarithmic (dB) units. The power p_(EMAX,c) corresponds tothe linear value of P_(EMAX,c) which is provided by higher layers forserving cell c.

P _(CMAXM) _(_) _(H,m)=MIN{10 log₁₀ Σp _(EMAX,c) ,P _(PowerClass) ,P_(eNB,m)}  Equation (18)

In the above, the sum may be over serving cells c belonging to cellgroup m only.

The lower bound may be set according to the following:

P _(CMAXM) _(_) _(L,m)=MIN{10 log₁₀(p _(eNB,m))−ΔT _(C),10 log₁₀ Σp_(EMAX,c) −ΔT _(C) ,P _(PowerClass)−MAX(MPR+A-MPR+ΔT _(IB,c) +ΔT _(C),P-MPR)}   Equation (19)

In the above, the sum may be over serving cells c belonging to cellgroup m only. The parameters ΔT_(IB,c) and ΔT_(C) may correspond totolerance values that depend on the specific combination of frequencybands configured, P-MPR may correspond to a power management term, MPRand A-MPR may correspond to allowed maximum power reduction andadditional maximum power reduction, respectively, where the allowancesmay be due to higher order modulation and contiguously aggregatedtransmit bandwidth configuration, as well as possible additional RFrequirements.

The configured maximum power per MAC instance (or cell group) for agiven MAC instance m may be reported to the network using MAC or higherlayer signaling, for instance as part of a power headroom report. Thevalue for both MAC instances may be included in any power headroomreport transmitted to any eNB (or from any MAC instance). Alternatively,the value for a given MAC instance may be included in any report thatcontains power headroom information for at least one serving cellbelonging to this MAC instance.

Configured maximum power per cell P_(CMAX,c): In some solutions, theconfigured maximum power P_(CMAX,c) applicable to a serving cell may bebounded by a lower bound P_(CMAX) _(_) _(L,c) and an upper boundP_(CMAX) _(_) _(H,c), such that:

P _(CMAX) _(_) _(L,c) ≦P _(CMAX,c) ≦P _(CMAX) _(_) _(H,c)  Equation (20)

The upper bound P_(CMAX) _(_) _(H,c) may be set as the minimum valuebetween a maximum WTRU power P_(PowerClass), the assigned maximum powerP_(eNB,m) for the MAC instance (or cell group) m to which serving cell cbelongs, and a parameter P_(EMAX,c) which is provided by higher layersfor serving cell c.

P _(CMAX) _(_) _(H,c)=MIN{P _(eNB,m) ,P _(EMAX,c) ,P_(PowerClass)}  Equation (21)

The lower bound P_(CMAX) _(_) _(Lc) may be set according to thefollowing:

P _(CMAX) _(_) _(L,c)=MIN{MIN(P _(EMAX,c) P _(eNB,m))−ΔT _(C,c) ,P_(PowerClass)−MAX(MPR,c+A-MPR _(,c) +ΔT _(IB,c) +ΔT _(C,c) ,P-MPR_(,c))}  Equation (22)

In the above, the parameters ΔT_(IB,c) and ΔT_(C,c) may correspond totolerance values that depend on the specific combination of frequencybands configured and the specific frequency band of the cell group towhich serving cell c belongs, P-MPR_(c) may correspond to a powermanagement term for serving cell c, MPR_(c) and A-MPR_(c) may correspondto allowed maximum power reduction and additional maximum powerreduction, respectively, for serving cell c, where the allowances may bedue to higher order modulation and transmit bandwidth configuration, aswell as possible additional RF requirements.

Total configured maximum output power P_(CMAX): In some solutions, thetotal configured maximum output power may be bounded by a lower boundP_(CMAX) _(_) _(L) and an upper bound P_(CMAX) _(_) _(H), such that:

P _(CMAX) _(_) L≦P _(CMAX) ≦P _(CMAX) _(_) _(H)  Equation (23)

The upper bound P_(CMAX) _(_) _(H) may be set as the minimum valuebetween a maximum WTRU power P_(PowerClass), the sum of powersp_(EMAX,c) over all serving cells c (of all cell groups), and the sum oflinear values of the assigned maximum power p_(eNB,m) over all cellgroups m, where each term is converted to logarithmic (dB) units. Thepower p_(EMAX,c) corresponds to the linear value of P_(EMAX,c) which isprovided by higher layers for serving cell c.

P _(CMAX) _(_) _(H)=MIN{10 log₁₀ Σp _(EMAX,c) ,P _(PowerClass),10 log₁₀ΣP _(eNB,m)}   Equation (24)

The lower bound P_(CMAX) _(_) _(L) may be set according to thefollowing:

P _(CMAX) _(_) _(L)=MIN{10 log₁₀ΣMIN[p _(EMAX,c)/(Δt _(C,c)),p_(PowerClass)/(mpr _(c) a−mpr _(c) ·Δt _(C,c) ·Δt _(IB,c)),p_(PowerClass)/(pmpr_(c) ·Δt _(C,c))],MIN(P _(PowerClass),10 log₁₀ Σp_(eNB,m))}   Equation (25)

In the above, the first sum is over all serving cells c (of all cellgroups), and the second sum is over all cell groups m. The parametersΔt_(IB,c) and Δt_(C,c) may correspond to the linear values of tolerancesthat depend on the specific combination of frequency bands configuredand the specific frequency band of the cell group to which serving cellc belongs, pmpr_(c) may correspond to the linear value of a powermanagement term for serving cell c, mpr_(c) and a-mpr_(c), maycorrespond to the linear values of an allowed maximum power reductionand an additional maximum power reduction, respectively, for servingcell c, where the allowances may be due to higher order modulation andtransmit bandwidth configuration, as well as possible additional RFrequirements.

Alternatively, the lower and upper bounds P_(CMAX) _(_) _(L) andP_(CMAX) _(_) _(H) may be derived using the following formulas:

P _(CMAX) _(_) _(L)=MIN{P _(PowerClass) ,ΣP _(CMAXM) _(_) _(L,m)}  Equation (26)

P _(CMAX) _(_) _(H)=MIN{P _(PowerClass) ,ΣP _(CMAXM) _(_) _(H,m)}  Equation (27)

Power sharing—general case: In some approaches, the WTRU firstdetermines an adjusted maximum total power, (or assigned total power),P′_(CMAXM,m)(i) for each MAC instance. The adjusted maximum total powerP′_(CMAXM,m)(i) may correspond to a value lower than the non-adjustedmaximum P_(CMAXM,m)(i) if scaling needs to be performed because of themaximum over all transmissions P_(CMAX)(i). Once the adjusted maximumtotal power P′_(CMAXM,m)(i) is determined for each MAC instance, theWTRU may determine the transmission power of all transmissionsassociated to a MAC instance m by applying the scaling procedure overthese transmissions for a single maximum total power level ofP′_(CMAXM,m)(i). In case an adjusted maximum power per MAC instance isnot defined, the scaling procedure may be applied directly using thenon-adjusted maximum P_(CMAXM,m)(i)

The determination of the adjusted maximum total power for each MACinstance may be performed using the following procedure. In a firststep, the following sum of powers is calculated for each MAC instance:

p _(m) ^(tot)(i)=min(Σ_(tεM) _(m) P _(t)(i),P _(CMAX,m)(i))  Equation(28)

Where M_(m) refers to the set of transmissions associated to the MACinstance m. In some approaches, there may not be a hard limit on the sumof transmissions of a MAC instance P_(CMAXM,m)(i). In this case, theabove formula would simplify to:

p _(m) ^(tot)(i)=_(ΣtεM) _(m) P _(t)(i)  Equation (29)

The sum over MAC instances P^(tot)(i) is then calculated as:

p ^(tot)(i)=Σ_(m) P _(m) ^(tot)(i)  Equation (30)

In case the sum over MAC instances P^(tot)(i) is smaller than or equalto P_(CMAX)(i), the adjusted maximum total power for each MAC instance,P′_(CMAXM,m)(i), is set to P^(tot) _(m)(i). Otherwise, the set ofadjusted maximum total powers P′_(CMAXM,m)(i) may be determined based onthe set of P^(tot) _(m)(i) using one of different possible approaches.

Power sharing between MAC instances based on equal scaling: In oneapproach, the adjusted maximum total powers are determined by applyingthe same scaling factor w^(MAC)(i) to each MAC instance, such that themaximum P_(CMAX)(i) is not exceeded:

$\begin{matrix}{{w^{\; {MAC}}(i)} = \frac{P_{CMAX}(i)}{P^{\; {tot}}(i)}} & {{Equation}\mspace{14mu} (31)} \\{{P_{{CMAXM},m}^{\prime}(i)} = {{w^{\; {MAC}}(i)}{P_{m}^{\; {tot}}(i)}}} & {{Equation}\mspace{14mu} (32)}\end{matrix}$

Power sharing between MAC instances based on absolute priority: Inanother approach, the adjusted maximum total powers of each MAC instanceare determined based on a priority level (or order) r associated to eachMAC instance, such that any necessary adjustment is preferably appliedto the lower priority MAC instance(s). In the case of 2 MAC instances,without loss of generality MAC instance m=0 may have higher prioritythan MAC instance m=1. In this case the adjusted maximum total power ofeach MAC instance may be determined such that the total power assignedto the higher priority MAC instance is the sum of powers P^(tot) ₀(i),but not exceeding P_(cmax)(i), while any remaining power may be assignedto the lower priority MAC instance, as follows:

P′ _(CMAXM,0)(i)=min(P _(CMAX)(i),P ₀ ^(tot)(i))  Equation (33)

P′ _(CMAXM,1)(i)=P _(CMAX)(i)−P′ _(CMAXM,0)(i)  Equation (34)

Power sharing between MAC instances based on unequal scaling factors: Inanother approach, the scaling factors that are applied to each MACinstance w^(MAC) _(m)(i) to ensure that the total configured powerP_(CMAX)(i) is not exceeded, may be unequal according to a configuredratio. The ratio may be pre-determined or provided by higher layers. Forinstance, the value of the scaling factor applied to a primary MACinstance may be K times the value of the scaling factor applied to asecondary MAC instance:

$\begin{matrix}{{w_{0}^{\; {MAC}}(i)} = {K\mspace{11mu} {w_{1}^{\; {MAC}}(i)}}} & {{Equation}\mspace{14mu} (35)} \\{{P_{{CMAXM},m}^{\prime}(i)} = {{w_{m}^{\; {MAC}}(i)}{P_{m}^{\; {tot}}(i)}}} & {{Equation}\mspace{14mu} (36)} \\{{Thus},} & \; \\{{w_{0}^{\; {MAC}}(i)} = \frac{K\mspace{11mu} {P_{CMAX}(i)}}{{K\mspace{11mu} {P_{0}^{\; {tot}}(i)}} + {P_{1}^{\; {tot}}(i)}}} & {{Equation}\mspace{14mu} (37)} \\{{w_{1}^{\; {MAC}}(i)} = \frac{P_{CMAX}(i)}{{K\mspace{11mu} {P_{0}^{\; {tot}}(i)}} + {P_{1}^{\; {tot}}(i)}}} & {{Equation}\mspace{14mu} (38)}\end{matrix}$

Power sharing between MAC instances based on guaranteed available power:The scaling factors w^(MAC) _(m)(i) may also be set to ensure that theadjusted maximum power per MAC instance m cannot be scaled down to avalue less than a guaranteed available power P^(g) _(m)(i). Expresseddifferently, in case the total maximum power over transmissions of allMAC instances would exceed P_(cmax)(i), scaling may be applied to theadjusted maximum power of one or more MAC instances, such that the totaltransmission power per MAC instance on which scaling is applied is notless than a guaranteed available power P^(g) _(m)(i).

In such a case, the scaling factor can be calculated as follows:

$\begin{matrix}{{{w_{m}^{\; {MAC}}(i)} = {\frac{1}{P_{m}^{\; {tot}}(i)}{\max\left\lbrack {{P_{m}^{\; g}(i)},{{P_{CMAX}(i)} - {\sum\limits_{m^{\prime} \neq m}\; {P_{m^{\prime}}^{\; {tot}}(i)}}}} \right\rbrack}}}\mspace{79mu} {{{if}\mspace{14mu} {P_{m}^{\; {tot}}(i)}} > {P_{m}^{\; g}(i)}}} & {{Equation}\mspace{14mu} (39)}\end{matrix}$

where the above scaling may only be applied if the total power over MACinstances P^(tot)(i) exceeds P_(cmax)(i). P In the case of two MACinstances, the above expression simplifies to:

$\begin{matrix}{{{w_{0}^{\; {MAC}}(i)} = {\frac{1}{P_{0}^{\; {tot}}(i)}{\max\left\lbrack {{P_{0}^{\; g}(i)},{{P_{CMAX}(i)} - {P_{1}^{\; {tot}}(i)}}} \right\rbrack}}}{{{if}\mspace{14mu} {P_{0}^{\; {tot}}(i)}} > {P_{0}^{\; g}(i)}}} & {{Equation}\mspace{14mu} (40)} \\{{{w_{1}^{\; {MAC}}(i)} = {\frac{1}{P_{1}^{\; {tot}}(i)}{\max\left\lbrack {{P_{1}^{\; g}(i)},{{P_{CMAX}(i)} - {P_{0}^{\; {tot}}(i)}}} \right\rbrack}}}{{{if}\mspace{14mu} {P_{0}^{\; {tot}}(i)}} > {P_{1}^{\; g}(i)}}} & {{Equation}\mspace{14mu} (41)}\end{matrix}$

The above means that the adjusted maximum power per MAC instance wouldbe set according to:

$\begin{matrix}{{{P_{{CMAXM},0}^{\prime}(i)} = {{{w_{0}^{\; {MAC}}(i)}{P_{0}^{\; {tot}}(i)}} = {\max\left\lbrack {{P_{0}^{\; g}(i)},{{P_{CMAX}(i)} - {P_{1}^{\; {tot}}(i)}}} \right\rbrack}}}\mspace{79mu} {{{if}\mspace{14mu} {P_{0}^{\; {tot}}(i)}} > {P_{0}^{\; g}(i)}}} & {{Equation}\mspace{14mu} (42)} \\{{{P_{{CMAXM},1}^{\prime}(i)} = {{{w_{1}^{\; {MAC}}(i)}{P_{1}^{\; {tot}}(i)}} = {\max\left\lbrack {{P_{1}^{\; g}(i)},{{P_{CMAX}(i)} - {P_{0}^{\; {tot}}(i)}}} \right\rbrack}}}\mspace{79mu} {{{if}\mspace{14mu} {P_{1}^{\; {tot}}(i)}} > {P_{1}^{\; g}(i)}}} & {{Equation}\mspace{14mu} (43)}\end{matrix}$

In the case of two MAC instances (e.g. corresponding to MeNB and SeNB),the guaranteed available power of one MAC instance (say MeNB) may bederived from the guaranteed available power of the other MAC instance(say MeNB). For instance, the guaranteed available power for SeNB may bedetermined as the difference between P_(CMAX)(i). and the guaranteedavailable power for MeNB (in linear units), such that the sum ofguaranteed available powers corresponds to the total configured maximumoutput power P_(CMAX)(i).

In some approaches, the guaranteed available power for a certain MACinstance may be defined to be zero. For example, the guaranteedavailable power for a MAC instance corresponding to SeNB may bedetermined to be zero.

In some approaches, the WTRU may ensure that at least the guaranteedavailable power is available to a first MAC instance at any given timeand may allocate remaining power, if any, as a function of itscapability to consider transmissions of a second MAC instance thatoccurs later in time for the unsynchronized mode of operation. Forexample, in case the WTRU is capable of considering power allocated tooverlapping transmissions of a second MAC instance that would startlater in time, the WTRU may allocate additional power to a first MACinstance up to the difference between the maximum transmit poweravailable to the WTRU and the power required by the second MAC instance.For example, in case the WTRU is not capable of considering powerallocated to transmissions of a second MAC instance that would startlater in time, the WTRU may allocate power to a first MAC instance up tothe difference between the maximum transmit power available to the WTRUand the guaranteed available power of the second MAC instance.Alternatively, in case the WTRU is not capable of considering powerallocated to transmissions of a second MAC instance that would startlater in time, the WTRU may allocate power to a first MAC instance up tothe difference between the maximum transmit power available to the WTRUand the power allocated for transmissions of the second MAC instance atthe time the WTRU starts transmission for the first MAC instance.

FIG. 15 illustrates an example procedure 1560 which may be implemented,for example, for allocation of remaining power as shown and describedwith respect to step 1260 of FIG. 12. In the example shown in FIG. 15,remaining power is allocated on a first-in-time basis to CG1 or CG2 forthe asynchronous case.

Within step 1560, the WTRU may first determine in step 1510 whetheruplink transmissions scheduled to be transmitted from the WTRU using theuplink resources of CG1 and to CG2 are asynchronous (as shown anddescribed with respect to FIG. 4 for example). If so, the WTRU maydetermine in step 1520 whether the first uplink transmission using theuplink resources of CG1 which is scheduled in the time interval beginsearlier in time than the first uplink transmission using the resourcesof CG2 which is scheduled in the time interval. If so, the remainingpower is allocated for uplink transmissions using the uplink resourcesof CG1 in step 1530. If not, the remaining power is allocated for uplinktransmissions using the uplink resources of CG2 in step 1540. In someimplementations, the allocation in step 1530 and/or step 1540 may beperformed using prioritization of the scheduled uplink transmissionsaccording to any of the methods described herein.

In some approaches, the WTRU may be configured with a different set ofvalues for the power levels (either for maximum power, or minimumguaranteed power) for each MAC entity. For example, the WTRU may beconfigured with a first set, that may contain one value of each MACentity that corresponds to a minimum guaranteed power and for which thesum of all values corresponds to a value that is less than the totalamount of available power for the WTRU, and with a second set for whichthe sum corresponds to the total amount of available power for the WTRU.In this case, the WTRU may use the first set of values if it is capableof considering the transmissions of both MAC entities when it determineshow to allocate power to each transmission in a given subframe while itmay use the second set of values otherwise. For example, the network maydetermine suitable values for both types of behavior such that a WTRUimplementation may be given the freedom to determine what powerallocation method to use depending on the observed timing betweentransmissions for both MAC entities.

In some approaches, the WTRU may ensure that at least the guaranteedavailable power is available to a first MAC instance at any given timeand may allocate remaining power, if any, as a function of itscapability to perform only reactive power allocation or also proactivepower allocation when the WTRU also performs transmissions for a secondMAC instance that occur later in time for the unsynchronized mode ofoperation. For example, in case the WTRU is only capable of reactivepower allocation or if the first MAC instance has higher priority, theWTRU may perform reactive power allocation and limit the power availableto a second MAC instance to the maximum between the minimum guaranteedpower for the second MAC instance and the difference between the maximumtransmit power available to the WTRU and the power required for thefirst MAC instance. For example, in case the WTRU is only capable ofreactive power allocation or if the second MAC instance has higherpriority, the WTRU may perform reactive power allocation and limit thepower available to the first MAC instance to the minimum guaranteedpower for the first MAC instance. For example, in case the WTRU iscapable of proactive power allocation and if the second MAC instance hashigher priority, the WTRU may perform proactive power allocation andlimit the power available to a first MAC instance to the maximum betweenthe minimum guaranteed power for the first MAC instance and thedifference between the maximum transmit power available to the WTRU andthe power required for the second MAC instance.

Approaches used for the determination of the guaranteed available powerare further described herein.

Unequal scaling for multiple priority levels: In another approach, alltransmissions may be scaled with different scaling values depending onthe priority level. To determine the appropriate scaling value, a WTRUmay be preconfigured with a scaling ratio to be applied to differenttransmissions of different priority. The scaling ratio may be providedfor each priority level. For example, a transmission of priority q#0 mayhave a scaling ratio when compared to a transmission of priority q=0,namely Δ_(q)=w_(q)(i)/w_(O)(i). A WTRU that is expected to have multipletransmissions in a TTI may determine the total required power for alltransmissions as

Σ_(tεT) _(q) _(∀) _(q) P _(t)(i)=Σ_(q)α_(q)(i)P _(CMAX)(i)  Equation(44)

where Σ_(tεT) _(q) P_(t)(i)=α_(q)(i)P_(CMAX) (i).

If the total required power does not exceed P_(CMAX)(i), the WTRU neednot scale any transmissions. However, if the total required powerexceeds P_(CMAX)(i), the WTRU may perform scaling on all transmissionsby using the appropriate scaling ratios. The WTRU may thus solve thefollowing equations to determine the set of scaling factorsw_(q)(i)=w_(q)(i) ∀tεT_(q):

Σ_(q) w _(q)(i)α_(q)(i)P _(CMAX)(i)=P _(CMAX)(i)  Equation (45)

w _(q)(i)=w ₀(i)Δ_(q) ,∀q>0  Equation (46)

The values of Δ_(q) may be updated based on the results of the mostrecent scaling in manners described herein for updating priority ofMACs. Furthermore, a WTRU may be configured with minimum transmissionpower such that a higher priority transmission may never be below apreconfigured value. In such a case, solving for the above equations mayresult in high priority transmissions being allocated insufficientpower. The WTRU may thus first solve for the equations, then if a firstpriority transmission is allocated insufficient power, the WTRU mayremove power allocated from a (or multiple) lowest prioritytransmission(s) and assign it to the first priority transmission untilsufficient power is achieved. The same can be done for the secondpriority transmission until all transmission power is exhausted and soon so forth in order of decreasing priority. In such an approach it ispossible that one or multiple lower priority transmissions are no longerallocated any transmission power and in such a case the UL transmissionis considered interrupted due to priority rules.

As an illustrative example, based on the above formulas, a firstpriority transmission (q=0) may be allocated β W, a second prioritytransmission (e.g. q=1) may be allocated p W and a third prioritytransmission (e.g. q=2) may be allocated φ W. However, the firstpriority transmission may have a minimum required transmission power ofγ W, where γ>β. The WTRU may thus reallocate γ−β W from the lowestpriority transmission and the resulting power allocation may be given byβ W for the first priority transmission, p W for the second prioritytransmission and φ−(γ−β) W for the third priority transmission. Ifφ−(γ−β)<0 then to satisfy the power requirements of the first prioritytransmission, some power allocated from the second priority transmissionmay be reallocated to the first priority transmission, such that theresulting power allocation may be given by β W for the first prioritytransmission, ρ−(γ−β−φ) W for the second priority transmission and 0 Wfor the third priority transmission. After satisfying the powerrequirements for transmission(s) of a certain priority, the same can bedone for the transmissions of the next priority.

In a different approach to achieve unequal scaling, a WTRU may beprovided a set of scaling ratios (δ₁, δ₂, . . . ) that may be used in arecursive manner as explained below. First the WTRU determines thetransmission power for all intended transmissions of any priority q(Σ_(tεT) _(q) P_(t)(i)=α_(q)(i)P_(CMAX)(i)). If the sum of those powersis greater than P_(CMAX)(i), unequal scaling may apply. The unequalpower scaling algorithm is performed by following these steps:

Determine the scaling of the highest priority (e.g. q=0) transmission(s)when compared to all other priority transmissions. The WTRU isconfigured with a first scaling ratio, δ₁ to be used in the followingmanner:

w ₀(i)α₀(i)P _(CMAX)(i)+δ₁ w ₀(i)Σ_(q>0)α_(q)(i)P _(CMAX)(i)=P_(CMAX)(i)  Equation (47)

The scaling used for the highest priority transmissions (w₀(0) mayremain fixed for the remainder of this algorithm. To determine thescaling factor of subsequent priority transmissions (e.g. q=1,2,3, . . .), first remove the power allocated to the (k−1)^(th) prioritytransmissions from the remaining available power:

P _(k)(i)=P _(k-1)(i)−w _(k-1)(i)α_(k-1)(i)P _(CMAX)(i),k>0  Equation(48)

Where

P ₀(i)=P _(CMAX)(i)  Equation (49)

Next, determine the power scaling of the k^(th) priority transmissionsin a similar manner to the first step:

w _(k)(i)α_(k)(i)P _(CMAX)(i)+δ_(k) w _(k)(i)Σ_(q>k)α_(q)(i)P_(CMAX)(i)=P _(k)(i)  Equation (50)

Repeat steps (b) and (c) until all transmissions have been allocatedpower.

Power scaling with combination of guaranteed available power andpriority criteria: The following paragraphs describe how power scalingcould be performed using a combination of concepts described herein,such as guaranteed available power for a cell group and the use ofpriority levels. Such procedure may be referred to as an “overallscaling procedure” and may involve multiple applications of scalingprocedures as will be described.

The following description assumes, without loss of generality, that two(2) cell groups (CGs) are defined. The starting point (input) of theoverall scaling procedure is a set of desired power levels for atransmission t denoted as P^(d) _(t)(i), and the output of the overallscaling procedure is a set of scaled power levels for transmission tdenoted as P^(s) _(t)(i). The overall scaling weight w_(t)(i) may thenbe defined as the ratio between the scaled power level and the desiredpower level, i.e. w_(t)(i) may be set as P^(s) _(t)(i)/P^(d) _(t)(i).

The calculation of the desired power level P^(d) _(t)(i) may be obtainedfrom known power control solutions involving an open-loop component,closed-loop adjustments, parameters obtained from physical layer orhigher layer signaling. The desired power level may be assumed to havebeen subject to a limitation on a per-cell basis such as P_(CMAX,c)(i).Additionally, in some solutions, in case the sum of desired powers oftransmissions for a cell group m exceeds a configured maximum power percell group P_(CMAXM,m)(i), the WTRU may perform the scaling procedureover the desired powers P^(d) _(t)(i) of transmissions for this cellgroup using a maximum total power level corresponding to P_(CMAXM,m)(i).To simplify the subsequent description the output of such scalingprocedure, if applied, is still referred to as “desired power” P^(d)_(t)(i).

The WTRU may be configured with a guaranteed available power for one orboth cell groups m, P^(g) _(m)(i). In case no guaranteed available poweris configured for a cell group, the WTRU may assume that the guaranteedavailable power for this cell group is zero.

The WTRU may first calculate the sum of powers for each cell group m,p_(m) ^(tot)(i), and the sum of powers over MAC instances P^(tot)(i)according to formulas already described but where P_(t)(i) maycorrespond to the desired power P^(d) _(t)(i). In case the sum over MACinstances P^(tot)(i) is smaller than or equal to P_(CMAX)(i), no furtheraction may be required to scale down the powers, such that P^(s)_(t)(i)=P^(d) _(t)(i) for all transmissions.

Otherwise, if P^(tot)(i) is larger than P_(CMAX)(i), the WTRU maydetermine, for each of the cell groups, whether the sum of desiredpowers P_(m) ^(tot)(i) is less than or equal to the correspondingguaranteed available power P^(g) _(m)(i). In case this condition wouldbe satisfied for a first cell group (m=0), the WTRU may not perform anyscaling of the powers of transmissions of this first cell group, i.e.P^(s) _(t)(i)=P^(d) _(t)(i) for transmissions belonging to this firstcell group. The WTRU may then perform the scaling procedure over thedesired powers P^(d) _(t)(i) of transmissions of the second cell group(m=1) using a maximum total power level corresponding to the differencebetween P_(CMAX)(i) and the sum of powers of the first cell group p₀^(tot)(i), i.e. P_(CMAX)(i)−p₀ ^(tot)(i), and the outcome of thisprocedure is the set of scaled power levels P^(s) _(t)(i) fortransmissions belonging to the second cell group.

Conversely, in case this condition would be satisfied for a second cellgroup (m=1), the WTRU may not perform any scaling of the powers oftransmissions of this second cell group, i.e. P^(s) _(t)(i)=P^(d)_(t)(i) for transmissions belonging to this second cell group. The WTRUmay perform the scaling procedure over the desired powers P^(d) _(t)(i)of transmissions of the first cell group (m=0) using a maximum totalpower level corresponding to the difference between P_(CMAX)(i) and thesum of powers of the second cell group P₁ ^(tot)(i), and the outcome ofthis procedure is the set of scaled power levels P^(s) _(t)(i) fortransmissions belonging to the first cell group.

Otherwise, in case the sum of desired powers P_(m) ^(tot)(i) is morethan the corresponding guaranteed available power P^(g) _(m)(i) for bothcell groups m=0 and m=1, different solutions may be envisioned to sharethe power between cell groups and scale powers, including solutions asdescribed in the following.

First solution: scaling by cell group followed by scaling over both cellgroups. In a first solution, the WTRU may start by performing, for eachcell group m, the scaling procedure over the desired powers oftransmissions of the cell group using a maximum total power levelcorresponding to the difference between P_(CMAX)(i) and the guaranteedavailable power P^(g) _(m′)(i) of the other group m′. In other words,the maximum total power level considered for a first cell group m=0 maybe set to P_(CMAX)(i)−P^(g) ₁(i) and the maximum total power levelconsidered for a second cell group m=1, may be set to P_(CMAX)(i)−P^(g)₀(i). As a result of this process, the WTRU has obtained a set ofinitially scaled transmission powers P^(is) _(t)(i) from both cellgroups. However, the sum of these initially scaled transmission powersP^(is) _(t)(i) over both cell groups may in general still exceedP_(CMAX)(i). If this is the case, the WTRU may perform an additionalscaling procedure over all initially scaled transmission powers P^(is)_(t)(i) of both cell groups for a maximum of P^(CMAX)(i), to obtain thescaled transmission powers P^(s) _(t)(i). As described previously,multiple priority levels may be considered for the transmissions whenperforming the scaling procedure. A priority order may be defined, basedfor instance on the type of physical channel of each transmission, thetype of uplink control information carried by each transmission, thecell group to which the transmission belongs, and may depend on whethera network indication was received. The overall procedure is completedafter the final transmission powers have been obtained.

Second solution: scaling on guaranteed power followed by scaling onnon-guaranteed power over both cell groups. In a second solution, thescaled power levels P^(s) _(t)(i) are calculated as the sum of twoportions P^(gua) _(t)(i) and P^(ngua) _(t)(i), where P^(gua) _(t)(i) isa portion obtained from the guaranteed available power for the cellgroup to which the transmission t belong, and P^(ngua) _(t)(i) is aportion obtained from power that is not guaranteed to any cell group.Each or both portions may be zero, or may correspond to the desiredpower level.

The WTRU may start by performing, for each cell group m, the scalingprocedure over the desired powers of transmissions of the cell group fora maximum level corresponding to the guaranteed available power P^(g)_(m)(i) of the cell group. As a result of this process, the WTRU hasobtained the set of portions from the guaranteed available power P^(gua)_(t)(i).

In case the sum of guaranteed available power P^(g) _(m)(i) over cellgroups is smaller than P_(CMAX)(i), the portion obtained from power notguaranteed to any cell group P^(ngua) _(t)(i) may be more than zero. Theset of portions P^(ngua) _(t)(i) may be calculated as the output of anadditional scaling procedure performed over all transmissions of bothcell groups for which the portions from the guaranteed available powerP^(gua) _(t)(i) is less than the desired power P^(d) _(t)(i). Thepre-scaled power used as a input to this scaling procedure for each suchtransmission may be the difference between the desired power and theportion from the guaranteed available power P^(d) _(t)(i)−P^(gua)_(t)(i). The maximum power used in the scaling procedure may be thenon-guaranteed available power P_(CMAX)(i)−P^(g) ₀(i)−P^(g) _(i)(i). Thepriority order used in the scaling procedure may be defined as in theprevious solution.

Third solution: allocation by cell group followed by scaling by cellgroup for one or both cell group(s). In a third solution, the WTRU maystart by identifying a relative priority (i.e. ranking) between cellgroups, based on at least one priority criteria. The priority criteriamay include one or more of the type of UCI contained in transmissions ofthe cell group, or the highest priority type of UCI among transmissionsof the cell group, the identity of the cell group itself (i.e. whetherit is a master or secondary CG), and may depend on whether a networkindication was received. When a priority criterion based on the type ofUCI or transmission is used (such as PUCCH over PUSCH without UCI, orHARQ A/N over CSI over no UCI) the priority for a CG may be determinedbased on the highest priority among all transmissions of the cell group,or alternatively only among transmissions of the cell group for whichscaling would need to be applied if only the guaranteed available powerwould be available to the cell group. Without loss of generality, thehigh-priority CG may be identified with index m=H and the low-priorityCG with index m=L. Then, the portion of the total available powerP_(CMAX)(i) that is not guaranteed to any cell group may be assigned inpriority to the highest priority cell group, while the low priority cellgroup can be assigned any remaining power, such that the assignedmaximum total power for the high and low priority cell groups,P′_(CMAXM,H)(i) and P′_(CMAXM,L)(i), respectively, may be set accordingto:

P′ _(CMAXM,H)(i)=min[P _(CMAX)(i)−P ^(g) _(L)(i),P _(H)^(tot)(i)]  Equation (51)

P′ _(CMAXM,L)(i)=P _(CMAX)(i)−P′ _(CMAXM,H)(i)  Equation (52)

In a second step, the WTRU performs the scaling procedure overtransmissions of the low priority cell group using a maximum ofV_(CMAXM,L)(i), and the output of this procedure is the set of scaledpowers for transmissions of the low priority cell group. In case the sumof desired powers P_(H) ^(tot)(i) of the high priority cell group wouldexceed the difference P_(CMAX)(i)-P^(g) _(L)(i), the WTRU also performsthe scaling procedure over transmissions of the high priority cell groupusing a maximum of P′_(CMAXM,H)(i), and the output of this procedure isthe set of scaled powers for transmissions belonging to thehigh-priority cell group. Otherwise no scaling is applied on the powersof the transmissions of the high-priority cell group, i.e. P^(s)_(t)(i)=P^(d) _(t)(i) for transmissions of this cell group.

Power scaling with unsynchronized transmissions: Transmissions takingplace for different MAC instances (or for different sets of servingcells) may not be synchronized at the subframe level. This means thattransmissions pertaining to a first MAC instance for a subframe may havealready started at the time transmission pertaining to a second MACinstance start. The following paragraphs describe approaches to handlepower scaling in such situations. Possibly, solutions described in thefollowing may apply in case the timing difference between subframes ismore than a specific duration, such as that of a single OFDM symbol.

It is assumed that transmissions may be categorized in two subsets A andB, where all transmissions of a given subset (for a subframe) start atthe same time, while transmissions in different subsets may not start atthe same time. For instance, subframe i of transmissions of subset A maystart at the third OFDM symbol of subframe i of transmissions of subsetB. In an example, the subsets A and B may correspond to transmissions ofa primary and a secondary MAC instance, respectively.

In a case where transmissions are not synchronized between cell groups(or MAC instances), the total configured maximum output power insubframe i, P_(CMAX)(i), may be determined according to the followingprocedure. The WTRU may determine a lower limit P_(CMAX) _(_) _(L) and ahigher limit P_(CMAX) _(_) _(H) for two portions of subframe i of subsetA, where the first portion overlaps with subframe j of subset B and thesecond portion overlaps with subframe j+1 of subset B. These limits aredenoted as follows:

-   -   P_(CMAX) _(_) _(L)(i,j), is the lower limit for the portion of        subframe i of subset A that overlaps with subframe j of subset        B;    -   P_(CMAX) _(_) _(L)(i,j+1)} is the lower limit for the portion of        subframe i of subset A that overlaps with subframe j+1 of subset        B;    -   P_(CMAX) _(_) _(H)(i, j) is the higher limit for the portion of        subframe i of subset A that overlaps with subframe j of subset        B;    -   P_(CMAX) _(_) _(H)(i, j+1) is the higher limit for the portion        of subframe i of subset A that overlaps with subframe j+1 of        subset B.        These limits may be determined based on formulas already        described, where it is understood that the values of the        parameters (such as maximum power reduction) may depend on the        actual transmissions taking place in the corresponding portion        of the subframe. The total configured maximum output power in        subframe i, P_(CMAX)(i), may then be bounded according to the        following:

P _(CMAX) _(_) L(i)≦P _(CMAX)(i)≦P _(CMAX) _(_) _(H)(i),   Equation (53)

where

P _(CMAX) _(_) _(L)(i)=MIN{P _(CMAX) _(_) _(L)(i,j),P _(CMAX) _(_)_(L)(i,j+1)}  Equation (54)

P _(CMAX) _(_) _(H)(i)=MAX{P _(CMAX) _(_) _(H)(i,j),P _(CMAX) _(_)_(H)(i,j+1)}  Equation (55)

In addition, P_(PowerClass) cannot be exceeded during any period oftime. Alternatively, one may calculate the limits according to thefollowing:

P _(CMAX) _(_) _(L)=MIN{P _(PowerClass) ,P _(CMAXM) _(_) _(L,A)(i)+MIN{P_(CMAXM) _(_) _(L,B)(j),P _(CMAXM) _(_) _(L,B)(j+1)}   Equation (56)

P _(CMAX) _(_) H=MIN{P _(PowerClass) ,P _(CMAXM) _(_) _(H,A)(i)+MAX{P_(CMAXM) _(_) _(H,B)(j),P _(CMAXM) _(_) _(H,B)(j+1)},   Equation (57)

Where P_(CMAXM) _(_) _(L,A)(i), P_(CMAXM) _(_) _(H, A)(i) are the lowerand upper limits of the configured maximum power per MAC instance (orcell group) A in subframe i, and P_(CMAXM) _(_) _(L,B)(j), P_(CMAXM)_(_) _(H, A)(j) are the lower and upper limits of the configured maximumpower per MAC instance (or cell group) B in subframe j.

Taking subset A as a reference, power scaling in a subframe i for thissubset may be dependent on, or jointly determined with, the powers ofthe following transmissions:

Transmissions of subset B for subframe j; and

Transmissions of subset B for subframe j+1;

where the end of subframe j for subset B occurs between the start andend of subframe i for subset A.

FIG. 16 shows a flow chart 1600 which illustrates determination by aWTRU of a maximum power available for all uplink transmissions during atime interval (Pcmax) for an asynchronous case.

In step 1610, the WTRU may determine whether a subframe i scheduled fortransmission using the uplink resources of CG1 asynchronously overlaps asubframe j scheduled for transmission using the uplink resources of CG2(i.e. the difference in start times of subframe i and subframe j exceedsa threshold for synchronicity as described with respect to FIGS. 2 and3). If frames i and j overlap asynchronously, the WTRU may determine instep 1620 whether subframe i begins before subframe j.

If subframe i begins before subframe j, the WTRU may determine Pcmax instep 1630 based on subframe i, subframe j, and subframe j−1 (i.e., thepreceding frame scheduled for uplink transmission using the uplinkresources of CG2) overlapping subframe i in time. A first range may bedetermined by the WTRU based on subframe i and subframe j, and a secondrange may be determined by the WTRU based on subframe i and subframej−1. A minimum value for Pcmax may then be determined by the WTRU as thelesser of the lowest value of the first and second ranges, and a maximumvalue for Pcmax may then be determined by the WTRU as the greater of thehighest value of the first range and the highest value of the secondrange. Pcmax will thus fall within a range between the minimum value andmaximum value.

If subframe i does not begin before subframe j, then the WTRU maydetermine Pcmax in step 1640 based on subframe j, the portion ofsubframe i overlapping subframe j in time, and the portion of subframei−1 (i.e., the preceding frame scheduled for uplink transmission to CG1)overlapping subframe j in time. A first range may be determined by theWTRU based on subframe i and subframe j, and a second range may bedetermined by the WTRU based on subframe i−1 and subframe j. A minimumvalue for Pcmax may then be determined by the WTRU as the lesser of thelowest value of the first and second ranges, and a maximum value forPcmax may then be determined by the WTRU as the greater of the highestvalue of the first range and the highest value of the second range.Pcmax will thus fall within a range between the minimum value andmaximum value. It is noted that for the asynchronous case, subframe iand subframe j by definition will never begin simultaneously.

FIG. 17 illustrates the subframes used by the WTRU to calculate Pcmax instep M30 as shown and described with respect to FIG. M. Subframe i isscheduled for transmission from the WTRU using the uplink resources ofCG1. Subframes j and j−1 are scheduled for transmission from the WTRUusing the uplink resources of CG2. Start time 1700 of subframe iprecedes start time 1710 of subframe j by time 1730, which exceeds athreshold for synchronicity as described with respect to FIGS. 2 and 3.For this asynchronous case, a first range may be determined by the WTRUbased on subframe i and subframe j, and a second range may be determinedby the WTRU based on subframe i and subframe j−1. A minimum value forPcmax may then be determined by the WTRU as the lesser of the lowestvalue of the first and second ranges, and a maximum value for Pcmax maythen be determined by the WTRU as the greater of the highest value ofthe first range and the highest value of the second range. Pcmax fortime interval 1730 will thus fall within a range between the minimumvalue and maximum value.

FIG. 18 illustrates the subframes used by the WTRU to calculate Pcmax instep 1640 as shown and described with respect to FIG. 16. Subframes iand i−1 are scheduled for transmission from the WTRU to CG1. Subframe jis scheduled for transmission from the WTRU to CG2. Start time 1800 ofsubframe i precedes start time 1810 of subframe j by time 1830, whichexceeds a threshold for synchronicity as described with respect to FIGS.3 and 4. For this asynchronous case, a first range may be determined bythe WTRU based on subframe i and subframe j, and a second range may bedetermined by the WTRU based on subframe i−1 and subframe j. A minimumvalue for Pcmax may then be determined by the WTRU as the lesser of thelowest value of the first and second ranges, and a maximum value forPcmax may then be determined by the WTRU as the greater of the highestvalue of the first range and the highest value of the second range.Pcmax for time interval 1830 will thus fall within a range between theminimum value and maximum value.

In an approach, power scaling of transmissions of subset A in subframe imay be performed taking into account the powers of transmissions ofsubset B for subframe j after scaling, which are on-going when subframei of subset A starts. For the purpose of determining the scalingfactors, the maximum configured output power P_(CMAX)(i) may be replacedwith a value P′_(CMAX)(i) (or remaining available power) correspondingto the difference between this value and the sum of the powers oftransmissions of subset B for subframe j after scaling, w_(t)(j)P_(t)(j):

P′ _(CMAX)(i)=P _(CMAX)(i)−Σ_(tεB) w _(t)(j)P _(t)(j)  Equation (58)

In a case where the term

P _(CG,B) ¹≡Σ_(tεB) w _(t)(j)P _(t)(j)  Equation (59)

is not constant over subframe j for transmissions of subset B, itsmaximum value over subframe j may be used. For instance, this couldoccur when SRS is transmitted in the last SC-FDMA symbol. The term

P _(CG,B) ¹≡Σ_(tεB) w _(t)(j)P _(t)(j)  Equation (60)

may be equivalent to the minimum value between the maximum power levelavailable to transmissions of subset B in subframe j, P′_(CMAXM,B)(j),and the sum of required powers for transmissions of subset B,

P _(qB)(j)≡Σ_(tεB) P _(t)(j)  Equation (61)

or possibly its maximum value over a subframe.

If subframe i has intra-subframe frequency hopping configured and theoverlapping period with subframe j of the subset B is less than or equalto a slot duration, then P′_(CMAX)(i) may take into consideration onlythe power level of the overlapping slot since the WTRU can change PApower level between slots in this case for the weight determination. Inaddition, if subframe i has scheduled SRS transmissions and theoverlapping period is less than a symbol, then P′_(CMAX)(i) may takeinto consideration only the power level of the overlapping symbol sincethe WTRU can change PA power level between SRS and shorten PUCCH/PUSCHin this case for the weight determination.

Reactive scaling: In an approach, the determination of scaling factorsfor transmissions of subset A in subframe i may be performed taking intoaccount the modified maximum power P′CMAX(i) as above and including inthe scaling procedure only the set of pre-scaled transmission powers ofsubset A in subframe i. In case there is an additional configured powerlimitation P_(CMAXM,A)(i) (or P′_(CMAXM,A)(i)) over transmissions ofsubset A, the scaling procedure may be performed using a maximum powerlevel corresponding to the minimum value between P′_(CMAX)(i) andP_(CMAXM,A)(i) (or P′_(CMAXM,A)(i)). Expressed differently, the maximumpower level used for the scaling procedure for transmissions of subset Ain subframe i, P′_(CMAXM,A)(i), may correspond to the minimum valuebetween P′_(CMAX)(i)=P_(CMAX)(i)-P¹ _(CG,B)(j) and a configured powerlimitation P_(CMAXM,A)(i), where the latter may correspond toP_(CMAX)(i) —P^(g) _(B) where P^(g) _(B) is a guaranteed powerconfigured for the cell group corresponding to transmissions of subset B(equivalently, to P_(CMAX)(i)×(1−R^(g) _(B)) if the guaranteed power isconfigured as a ratio of P_(CMAX)(i)). In this case, the maximum powerlevel P′_(CMAXM,A)(i) may also be expressed as P_(CMAX)(i)−max[P_(CMAX)(i) R^(g) _(B), P¹ _(CG,B)(j)].

Using this approach, the transmission powers of subset A are maximizedtaking into account the limitation brought by transmissions from subsetB finishing in this subframe, without considering the power requirementsof transmissions from subset B that will start in the subframe. Suchapproach may be referred to as “reactive scaling” herein.

Proactive scaling: Alternatively, the determination of scaling factorsfor transmissions of subset A in subframe i may be performed taking intoaccount the following:

The modified maximum power P′_(CMAX)(i) applicable to the portion of thesubframe i that ends when subframe j of subset B ends;

The maximum configured output power P_(CMAX)(i) applicable to theportion of the subframe i that starts when subframe j+1 of subset Bstarts;

The set of pre-scaled or desired P^(d) _(t)(j+1) transmission powers forsubframe j+1 of subset B.

Possible additional configured maximum power limits over subsets A and Bin subframes i and j+1, P_(CMAXM,A)(i) and P_(CMAXM,B)(j+1).

Using this approach, the transmission powers of subset A are maximizedtaking into account both the limitation brought by transmissions fromsubset B finishing in this subframe as well as the limitation brought bytransmissions from subset B starting in this subframe. Such approach maybe referred to as “proactive scaling” herein. When this approach isused, the scaling factors for transmission powers of subset A insubframe i, w_(t)(i) may be determined according to the followingprocedure.

-   -   Determine the scaling factors w⁽¹⁾ _(t)(i) or the scaled powers        P^(s(1)) _(t)(i) by applying a first scaling procedure over the        pre-scaled transmission powers P_(t)(i) or desired powers P^(d)        _(t)(i) of subset A only and using the modified maximum power        P′_(CMAX)(i), or the minimum value between P′_(CMAX)(i) and a        configured power limitation P_(CMAXM,A)(i) (or P′_(CMAXM,A)(i))        over transmissions of subset A;    -   Determine the scaling factors w⁽²⁾ _(t)(i) or the scaled powers        P^(s(2)) _(t)(i) by applying a second scaling procedure over the        pre-scaled transmission powers P_(t)(i) or desired powers P^(d)        _(t)(i) of subset A in subframe i, as well as the pre-scaled        transmission powers P_(t)(j+1) or desired powers P^(d) _(t)(j+1)        of subset B in subframe j, and using the maximum configured        output power P_(CMAX)(i); in case configured power limitations        over subsets A and B, P_(CMAXM,A)(i) and P_(CMAXM,B)(j+1), (or        P′_(CMAXM,A)(i) and P′_(CMAXM,B)(j)) are defined, the scaling        procedure may be performed according to an approach already        described for the case of power sharing between MAC instances        (or multiple scaling).    -   Select the minimum value between the two values for each scaling        factor (or for each scaled power):

w _(t)(i)=min[w _(t) ⁽¹⁾(i),w _(t) ⁽²⁾(i)]  Equation (62)

Or equivalently:

P ^(s) _(t)(i)=min[P ^(s(1)) _(t)(i),P ^(s(2)) _(t)(i)]  Equation (63)

Another possible solution may include the following, if subset A and Bcorrespond to MAC instances A and B respectively: Determine a tentativeassigned total power P′⁽¹⁾ _(CMAXM,A)(i) for the first part of thesubframe, corresponding to the minimum between the value P′_(CMAX)(i) aspreviously described and the configured maximum power P_(CMAXM,A)(i) forMAC instance A; determine a tentative assigned total power P′⁽²⁾_(CMAXM,A)(i) for the second part of the subframe, using one of thepreviously described solution for power sharing between MAC instances,where transmissions of a second MAC instance B for subframe j+1 areconsidered, as well as associated priorities if applicable; determinethe assigned total power P′_(CMAXM,A)(i) for (the whole) subframe i asthe minimum between both tentative assigned total powers, i.e.P′_(CMAXM,A)(i)=min{P′⁽¹⁾ _(CMAXM,A)(i), P′⁽²⁾ _(CMAXM,A)(i)}; and,determine the transmission powers of all transmissions associated to MACinstance A in subframe (i) by applying the scaling procedure over thesetransmissions for a single maximum total power level of P′_(CMAXM,A)(i).

In some solutions, the calculation may be performed by assuming that theassigned total power of subset B in subframe j+1 P′_(CMAXM,B)(j+1) isequal to a configured value corresponding to a guaranteed assigned powerfor subset B. Such approach may be useful if the actual requiredtransmission powers of subset B are not known at the time where thetransmission powers of subset A in subframe i need to be calculated. Insome solutions, whether a configured value of P′_(CMAXM,B)(j+1) is usedor whether a value is calculated based on actual required transmissionpowers may depend on whether the difference in timing between subframe iand subframe j+1 is below a threshold, or whether the available WTRUprocessing time between reception of control information applicable tosubset B in subframe j+1 and transmission of subset A in subframe i isbelow a threshold. For example, the WTRU may determine such differencein timing according to any of the methods described herein regardingsynchronous and unsynchronous uplink transmissions across cell groups,such as based on the type of uplink operation (synchronous orasynchronous) between subsets of transmissions. Alternatively, the WTRUmay determine the difference in timing according to any of the methodsdescribed herein regarding processing a time budget, such as based onWTRU processing time.

When proactive scaling is performed as in the above, the determinationof scaling for transmissions of subset B in subframe j+1 may beperformed immediately after by applying the reactive scaling procedure(applied from the perspective of subset B) using the scaling factorscalculated as above for subset A in the determination of P′_(CMAX)(j+1).This means that the scaling factors for both sets of transmissions maybe calculated without any interval in between.

With respect to the performance of a scaling procedure overtransmissions belonging to both subsets in the above, priorities andpossibly sub-priorities may be defined on each separate transmission. Inaddition, or alternatively, priorities may be defined on a subset basis.For instance, subset B may have higher priority than subset A if thosesubsets correspond to a primary MAC instance and a secondary MACinstance, respectively.

The WTRU may determine whether to apply “reactive scaling” or “proactivescaling” for a subset of transmissions based on at least one of thefollowing criteria.

In one example approach, the WTRU may apply reactive scaling to bothsubsets of transmissions always. In this case, a separate calculation isperformed at at least every start of a subframe of either subset oftransmissions.

In another example approach, the WTRU may apply reactive scaling on asubset of transmissions if the corresponding MAC instance is of higherpriority than the other MAC instance, based on any prioritizationsolution described herein.

In another example approach, the WTRU may apply proactive scaling forsubset A (and reactive scaling for subset B immediately after) if thetime difference between the start of subframe i and the start ofsubframe j+1 is less than a threshold. The threshold may be pre-definedand may correspond, for instance, to an allowable reduction of theavailable processing time for the WTRU to determine the requiredpre-scaled transmission powers of subset B. The threshold, or whetherproactive scaling is possible at all, may be dependent on a WTRUcapability signaled to the network. Alternatively, the threshold maycorrespond to half of a subframe, or to one slot. In this case,effectively a pairing of subframes is performed such that the timeinterval between the starts of paired subframes is minimized. Proactivescaling is then applied on the earlier subframe of this pair, andreactive scaling is applied on the later subframe. In another examplecase, this approach is only used if the earlier subframe corresponds totransmissions for a MAC instance of lower priority.

Reactive scaling with pre-emption: In some approaches, the WTRU maycalculate transmission powers for a first MAC instance in subframe iaccording to a reactive scaling procedure (i.e. taking into account onlytransmissions of a second MAC instance of subframe j which overlaps inthe early portion of subframe i) and drop transmissions for this firstMAC instance over all or a portion of the subframe in case it determinesthat the second MAC instance (or transmissions thereof) has higherpriority in subframe j+1 than the first MAC instance in subframe i.

In other words, the transmission powers of a first MAC instance insubframe i in at least a portion of subframe i, may be either the resultof the reactive scaling procedure, or zero, depending on whether thesecond MAC instance in subframe j+1 has higher priority than the firstMAC instance in subframe i.

In some approaches, the WTRU may calculate transmission powers for afirst MAC instance in subframe i according to a reactive scalingprocedure if it determines that the second MAC instance has lowerpriority (or possibly lower or equal priority) in subframe j+1, or if itdetermines that no transmission is present for the second MAC instancein subframe j+1. Otherwise, the WTRU may determine the transmissionpowers for the first MAC instance in subframe i based on applyingscaling using a pre-defined assigned total power P^(preempt)_(CMAXM,A)(i) as maximum power, possibly only if such value is smallerthan the remaining available power P′_(CMAX)(i) determined as part ofreactive scaling.

Such solutions may have the benefit of avoiding extensive calculationsor recalculations of powers when information about transmissions for thesecond MAC instance in subframe j+1 becomes available.

Further example applicable prioritization functions are described in thefollowing discussion. Related approaches include those that may beapplied when a WTRU is limited with respect to uplink operation. Forexample, such prioritization function may include at least one of thefollowing:

Selective blanking: The WTRU may determine that it should perform atransmission of a higher priority, and it may determine that it shouldnot perform a transmission of a lower priority (or allocate it zeropower, in which case it may be considered as a power scaling event).

This may be useful, for example, to perform some form of TDM between aplurality of MAC entities (e.g. primary, secondary) and/or between aplurality of physical channel (or signal) types (e.g. PUSCH, PUCCH,PRACH, SRS) and/or between a plurality of transmissions for a same typeof physical channel (e.g. PUSCH and PUSCH, PUCCH and PUCCH, etc.).

In particular, this may be useful when it can be assumed that timing ofthe uplink transmission can be synchronized within some margin, e.g. atthe symbol duration and within the length of a cyclic prefix.

Selective transmission: As described herein, the WTRU may determine thatit should perform a transmission such that it may autonomously determineone or more characteristics of the transmission as a replacement of oneor more aspects of the applicable grant (referred to as the base grant).

Truncated transmission: The WTRU may determine that it should perform atransmission of a higher priority, and it may determine that it shouldtruncate one or more symbols for a transmission of a lower priority.

For example, this may be useful to perform some form of TDM between aplurality of MAC entities (e.g. primary, secondary) and/or between aplurality of physical channel (or signal) types (e.g. PUSCH, PUCCH,PRACH, SRS) and/or between a plurality of transmissions for a same typeof physical channel (e.g. PUSCH and PUSCH, PUCCH and PUCCH, etc.).

In particular, this may be useful when it cannot be assumed that timingof the uplink transmission can be synchronized within some margin, e.g.at the symbol duration and within the length of a cyclic prefix.

Power scaling: The WTRU may determine that it should apply a scalingfunction on the transmission power of one or more uplink transmissions,such that power may be first allocated to a transmission of a higherpriority, and the remaining power may be allocated in decreasing orderof priority. Possibly, if the WTRU determines that the priority of twoor more transmissions is equal, the WTRU may apply additional priorityrules, it may allocate the remaining power equally or it may be afunction of the WTRUs implementation such that transmission power may beoptimized (e.g. the WTRU may determine the power allocation thatrequires the least backoff e.g. MPR applied).

Resource used for HARQ A/N or other UCI transmission: The WTRU maydetermine a type of resource (PUCCH or PUSCH) and/or an amount or aproportion of resources used for HARQ A/N or other UCI within PUSCH, toincrease the probability of successful detection of such UCI in case ofpower limitation. For instance, the number of coded symbols Q′ used forHARQ A/N or for rank indication (RI) may be determined as the output ofa prioritization function. For instance, the number of coded symbols Q′may be set to 4 times the number of sub-carriers of the PUSCH allocationinstead of the number calculated as per existing solutions, as a resultof the prioritization function. In another example, the prioritizationfunction may determine that HARQ A/N should be transmitted over PUCCHinstead of PUSCH and drop any PUSCH transmission.

The WTRU may determine a priority according to one or more rules, suchas those described herein. Such priority may be used as prioritizationlevel in association to a prioritization function such as describedabove.

Such prioritization function and prioritization level may be applicableto the selection of a grant to be used for uplink transmission(s) in agiven TTI (e.g. as in case 1 above). For example, the WTRU may havevalid grant for a primary MAC instance and one for a secondary MACinstance for a given TTI. If the WTRU applies selective transmission,the WTRU may select the grant for which to perform a transmission as afunction of the applicable priority level.

Alternatively, such prioritization function and prioritization level maybe applicable to the allocation of transmit power used for uplinktransmission(s) in a given TTI (e.g. as for case 2 and 3 above). Forexample, the WTRU may have a valid grant for a primary MAC instance andone for a secondary MAC instance for a given TTI. If the WTRU applies apower scaling function, the WTRU may determine what transmissionassociated to what MAC entity should be first allocated availabletransmission power, and then allocate any remaining power to uplinktransmission(s) associated to the other MAC entity. Possibly, if theremaining power is insufficient for the concerned transmission, the WTRUmay perform selective transmission (if applicable).

For any of the above prioritization functions, parameters representingthe concerned prioritization function may be a configuration aspect ofthe WTRU.

In an example, a prioritization function may be parametrized, i.e., thenetwork may be in control. For example, the WTRU may be configured for apower scaling function that includes a minimal amount of power toallocate to a specific MAC instance (e.g., a guaranteed available powerfor a MAC instance, P^(g) _(m)(i), as previously described), or to atarget power ratio to allocate for a specific MAC instance. Possibly,such threshold may be applied per physical channel (e.g. PUCCH, PUSCH).

In another example, in an approach, a guaranteed available power for aMAC instance P^(g) _(m)(i) may be derived from a value provided fromhigher layer signaling. The value may be expressed in terms of anabsolute value (e.g. in dBm or mW) or in terms of a fraction of a totalconfigured maximum output power P_(CMAX)(i) or of a maximum WTRU powerP_(PowerClass). For instance, the guaranteed available power for a MACinstance in subframe (i) may be determined to be X dB below P_(CMAX)(i)(expressed in dBm units), or may be determined to be Y times P_(CMAX)(i)(expressed in linear units), where Y corresponds to a ratio of powerthat is guaranteed to be available. The value of X (or Y) may beprovided by higher layers.

In another example, the WTRU may be configured with one or more set ofparameters for a given prioritization function. When multipleconfiguration are available for a given function, the WTRU may determinewhat function to apply in a given subframe as a function of semi-staticaspects (as described below) and/or as a function of dynamic aspects (asdescribed below). For example, for a power scaling function, differentthresholds may be configured e.g. such that default value(s) may beavailable and such that a non-default parameter (or set thereof) may beaddressed e.g. by control signaling received by the WTRU.

In other words, the WTRU may receive control signaling that dynamicallymodify the set of applicable prioritization rules.

In an example, the WTRU may be configured to use one of a possible setof guaranteed available powers for at least one MAC instance. The setmay be provided from higher layer signaling (e.g., RRC). The specificvalue of the guaranteed available power to use from the set may beprovided from physical layer signaling or from MAC signaling (MACcontrol element). For instance, the WTRU may determine the value of theset that should be used (for each MAC instance) based on a field of areceived DCI, possibly only if received from a specific MAC instance.The value may be applied only to a subframe associated to the DCI or toan uplink transmission associated to this DCI. Alternatively, the valuemay apply to all subsequent uplink transmissions until reception of anew indication.

In another example, the specific value of the guaranteed available powerto use from the set for a first MAC instance may depend on the relativepriority of this MAC instance compared to the second MAC instance. Suchrelative priority may depend on whether HARQ A/N is included in atransmission of the first or the second MAC instance. For instance, aset of possible values of the guaranteed available power for a first MACinstance may be 80%, 50% or 20% of P_(cmax)(i). In a case where thisfirst MAC instance has a lower priority than a second MAC instance, theguaranteed available power for the first MAC instance may be 20% ofP_(cmax)(i). In case both MAC instances have the same relative priority,the guaranteed available power for the first MAC instance may be 50% ofP_(cmax)(i). In a case where the first MAC instance has a higherpriority than a second MAC instance, the guaranteed available power forthe first MAC instance may be 80% of P_(cmax)(i).

This may be useful to enable operation whereby an eNB may control theswitching of the applicable priorities between transmissions for a givenWTRU using dynamic control signaling.

In another example, the values of parameters that may be used in a givenprioritization function may be function of a priority between MACinstances (cell groups) or between transmissions. For instance, themaximum power for MAC instance m, P_(CMAXM,m), may be a first valueP_(CMAXM,HIGH) in case this MAC instance is prioritized over theother(s), and a second value P_(CMAXM,LOW) in case this MAC instance isnot prioritized or has lower priority. In another example, theguaranteed available power P^(g) _(m)(i) may be a first value P^(g)_(HIGH)(i) in case this MAC instance is prioritized over the other(s),and a second value P^(g) _(Low)(i) in case this MAC instance is notprioritized or has lower priority.

Control of P_MeNB and P_SeNB are further discussed below.

Hard split between MAC entities for WTRU available power: The WTRU maybe configured (e.g. by RRC) with a value for PeNB,m=PeNB,0 for the MACentity associated to transmissions towards a MeNB (e.g. the primary MACentity) herein referred to as P_MeNB, and with a value for PeNB,m=PeNB,1for the MAC entity associated to transmissions towards a SeNB (e.g. thesecondary MAC entity) herein referred to as P_MeNB when configured withdual connectivity. Conceptually, such value may impact how muchtransmission power is needed before the WTRU determines that powerscaling should be applied; it also may impact the uplink coverage of theWTRU's transmission. When such values are semi-statically configuredusing L3 signalling, it may become challenging for the system tooptimize the WTRU's power usage while ensuring that uplink coverage(such as for the transmission of critical L3 signalling) can bemaintained. Methods to adjust such values dynamically are furtherdescribed herein.

Coefficient-based variable split between MAC entities for WTRU availablepower: In an example approach, the WTRU may additionally determine acoefficient value alpha to apply to the values of P_MeNB and P_SeNB. TheWTRU may then use alpha*P_MeNB and (1-alpha)*P_SeNB (in linear units),if necessary, for example, where the WTRU needs to determine how tosplit power for transmissions associated to more than one MAC entityand/or where the WTRU needs to apply a prioritization function (e.g. theWTRU is in a power-limited situation).

Adjustable split levels between MAC entities for WTRU available power:In an example approach, the WTRU may instead be configured such thatdifferent power allocation ratio may be applied. For example, the WTRUmay be configured with multiple pairs of values for [P_MeNB, P_SeNB].Alternatively, the WTRU may be configured with a set of alpha values.Possibly, each pair may be indexed.

WTRU-autonomous adjustment: The WTRU may autonomously determine theapplicable power allocation ratio.

The WTRU may become power-limited and change the ratio to allocateunused power to the concerned transmissions: In one example, the WTRUmay adjust such ratio if it determines that it is power-limited; theWTRU may determine that it has insufficient transmit power for aspecific period of time for transmissions associated to a given MACentity and determine that power may be reallocated such that more poweris made available to transmissions of the concerned MAC entity. This maybe done, for example, only if sufficient transmit power remainsavailable for transmissions associated to the other MAC entity, if any.Such period of time may be a single TTI (e.g. the occurrence of theapplication of a prioritization—e.g. power scaling—for a single TTI maytrigger such adjustment) or a plurality of TTIs. The WTRU may determinethe adjustment as a function of the power scaling levels applied duringsuch period such that power scaling may be minimized.

The WTRU may determine average power over a certain period andreallocate power levels accordingly: In one example, the WTRU may adjustsuch ratio if it determines that the power split used and the averagepower allocated to transmissions associated to each MAC entity do notmatch each other over a certain period. For example, the WTRU maydetermine that power used for transmissions associated to a first MACentity do not exceed in average an amount that correspond to anothervalue in the WTRU's configuration, which value (either alpha, or aP_MeNB, P_SeNB pair) may be used without impairing transmissionsassociated to the second MAC entity.

The WTRU may prioritize transmissions to which more power should beallocated: In another example, the WTRU may adjust such ratio if itdetermines that a change in prioritization of transmissions (e.g.according to any of the method described herein) should be applied. Forexample, the WTRU may adjust the ratio such that more power is madeavailable to transmissions associated to a primary MAC entity (i.e. theMAC entity associated to the eNB used for macro coverage) where data ofhigher priority (e.g. RRC signaling, including measurement report) isavailable for transmission. In another example, the WTRU may performsuch adjustment where it triggers a Scheduling Request (SR), or for asubframe in which the WTRU performs a SR transmission (either a preambletransmission for RA-SR, or a transmission on PUCCH for D-SR). In anotherexample, the WTRU may perform such adjustment when it performs apreamble transmission. Possibly, in the latter case, only for a preambletransmission associated to a contention-based random access procedure.

The WTRU may determine that it is moving towards the edge of a cell e.g.macro cell edge: In another example, the WTRU may adjust such ratio ifit determines that a change in its pathloss estimation for the physicallayer associated to a specific MAC entity changes by a certain amount.For example, the WTRU may adjust the ratio such that more power is madeavailable to transmissions associated to the primary MAC entity (i.e.the MAC entity associated to the eNB used for macro coverage) where theassociated pathloss estimate drops by a certain amount.

The rate of WTRU-autonomous adjustment may be limited: In one approach,the WTRU may limit how often it may autonomously adjust the split ofavailable power between transmissions of different MAC entities. Forexample, the WTRU may start a prohibit timer (which usage and/or valuemay possibly be configurable by the network) when it performs suchadjustment, such that no further WTRU-autonomous adjustment may be madewhile the timer is running. If used in combination withnetwork-controlled adjustments, the WTRU may restart such timer everytime it performs such adjustment as a result of a network-controlledprocedure. Possibly, the WTRU may consider only subframes for which itperforms simultaneous transmissions. Possibly, such timer may be the PHRprohibit timer, in particular if the WTRU triggers a PHR whenever itperform such adjustments autonomously.

The WTRU may determine that it operates according to singleconnectivity: In another example, the WTRU may adjust its powerallocation function such that a split is not applicable. In such case,the WTRU may revert to R11 power allocation functions. For example, theWTRU may determine that it may no longer perform any uplink transmission(possibly except for a preamble transmission) for the secondary MACentity e.g. when it no longer has a valid uplink timing advance (e.g.TAT is not running for any cell of the secondary MAC entity) or e.g.following a failure event for a procedure of the concerned MAC entitysuch as a RACH failure, a RLC failure or a radio link problem detectedby RLM and applicable to cell(s) of the concerned MAC entity. Forexample, the WTRU may determine that the configuration of the secondaryMAC entity is either removed or invalidated. For example, the WTRU mayinitiate a RRC connection re-establishment procedure.

NW-controlled adjustment: The WTRU may adjust the applicable powerallocation ratio when it receives control signaling from the network.For example, such control signaling may be received in a DCI on PDCCH(possibly only on the PDCCH associated to the PCell of the WTRU'sconfiguration), in a L2 MAC Control Element or in L3 RRC signaling (e.g.RRC reconfiguration procedure). For example, the WTRU may determine theindex of a pair of values for [P_MeNB, P_SeNB] or a coefficient alpha ina DCI. Possibly, such DCI may be a format 3 or 3a received byTPC-PU*CH-RNTI or similar. Possibly, such signaling may be a set of bits(e.g. TPC field, or frequency hopping field) in a DCI that grants uplinkresources for a transmission. Such adjustment may be applicable only toa single subframe, e.g. in particular if signaling together with theallocation of uplink resources for a transmission, or until furtherlogic is executed by the WTRU that adjusts the applicable power ratio todifferent values.

Applying the selected adjustments: If the WTRU determines that it shouldadjust the split of available power, it may apply the new valueaccording to at least one of the following: The WTRU may apply theadjustment only for the applicable transmission e.g. if receivedtogether with a DCI that allocated resources for an uplink transmission;the WTRU may apply the adjustment after a certain processing time e.g. Xsubframes after the subframe in which the WTRU could first determinethat an adjustment was required (for example, in case ofnetwork-controlled adjustment, in subframe n+x for control signalingreceived in subframe n); the WTRU may apply the adjustment in the firstsubframe that immediately follows a subframe for which the WTRU did notperform simultaneous transmissions i.e. after a subframe in which theWTRU either allocate power only for transmissions associated to a singleMAC entity or did not perform any transmission at all; (possibly, forthe first such subframe after a specific processing time); t WTRU mayautonomously determine that at least one transmission should be blankedsuch that such subframe is induced (such subframe may be part of aconfigured gap e.g. a measurement gap or a period for which the WTRU wasnot in DRX active time).

The WTRU may trigger PHR if it autonomously adjusts the power split forWTRU available power between MAC entities: In one approach, the WTRU maytrigger a notification to the network (e.g. either towards the MeNBonly, or possibly also to the SeNB) where it autonomously determinesthat a different split of available transmit power is used, e.g.according to any of the method described above. For example, the WTRUmay trigger a PHR in such case.

The WTRU may be configured for multiple prioritization functions: Forexample, the WTRU may be configured with one or more prioritizationfunction(s). When multiple functions are configured, the WTRU maydetermine what function to apply in a given subframe as a function ofsemi-static aspects (as described below) and/or as a function of dynamicaspects (as described below). For example, different functionsthresholds may be configured e.g. such that a default function may beavailable and such that a non-default function may be addressed bycontrol signaling received by the WTRU.

In an example, the WTRU may receive control signaling that dynamicallymodify the set of applicable prioritization function.

This may be useful to enable operation whereby an eNB may control theswitching of the prioritization function applied between transmissionsfor a given WTRU using dynamic control signaling.

In another example, the prioritization function applied by the WTRU in asubframe may depend on a priority level or priority order associated toa transmission pertaining to this MAC instance in this subframe, and/oron a relative priority between a transmission pertaining to this MACinstance and a transmission pertaining to another MAC instance. Forinstance, it may depend on whether HARQ A/N is included in atransmission of one or both MAC instances. In a case where atransmission with HARQ A/N is included in a first MAC instance but notin a second MAC instance, the prioritization function may comprise“power sharing based on an absolute priority” described further herein,where the higher priority MAC instance is the first MAC instance. Incase a transmission with HARQ A/N is included in both MAC instances, theprioritization function may comprise “power sharing based on an absolutepriority”, where the higher priority MAC instance is a pre-defined MACinstance (e.g. a primary MAC instance). In case no transmission withHARQ A/N is included in any MAC instance, the prioritization functionmay comprise “power sharing based on guaranteed available power”described further herein using a configured set of values for theguaranteed available power.

In another example, the prioritization function applied by the WTRU maydepend on an explicit indication received from a DCI from an existingfield (e.g. TPC command field) or a newly defined field. For instance,the WTRU may determine that “power sharing based on absolute priority”is performed in case this indication is received, and that “powersharing based on guaranteed available power” is performed otherwise.

Multiple prioritization functions may also be combined using precedencerules, as described further herein.

A function may be configured such that it is applicable in subset ofTTIs. For example, The WTRU may be configured such that a first priorityfunction may be applicable to a subset of subframes within a given radioframe, while a second priority function may be used for a second subsetof subframes within the concerned frame.

For example, the WTRU may be configured such that in a given set of TTIs(e.g. first TTI of a radio frame or subframe #0) the WTRU determinesthat selective transmission function may be applied to uplinktransmission of different priority levels while it may determine thatfor a second set of TTIs (e.g. the other TTIs in the radio frame orsubframe #1-#9) a power scaling function may be applied to uplinktransmissions of different priority levels. Possibly, in theconfiguration, all subframes may refer to timing associated to a singleMAC entity.

This may be useful to enable operation whereby some TDM is applied forthe uplink between MAC/PHY entities, while for other subframes powerdistribution and power scaling may be used between MAC/PHY entities in agiven subframe.

For any of the above prioritization functions, the WTRU may firstdetermine the priority level to associate to a given transmission in theconcerned TTI when applying the prioritization function. The WTRU maydetermine such priority level according to a number of approaches, orany combinations thereof, according to at least one of the following:

-   -   Dynamic aspects: The WTRU may determine the priority level of a        transmission as a function of the received control signaling        and/or operational state of the WTRU. Examples of such rules are        described herein.    -   Semi-static aspects: The WTRU may determine the priority level        of a transmission as a function of configurable rules. Examples        of such rules are described herein.    -   Static aspects: The WTRU may determine the priority level of a        transmission as a function of pre-defined rules. Examples of        such rules are described herein.

Similarly, the WTRU may determine the prioritization function (and/orthe corresponding set of parameters) to apply according to any of theabove aspects using similar approaches as those described to determinethe priority level to associate to a given transmission in a given TTI.In other words, the selection of the function to apply may itself beconsidered as a priority level for the concerned TTI.

In the approaches described below, a transmission may refer to any typeof uplink transmission; for example, while not limiting the belowapproaches to any other type of uplink transmissions, a WTRU may use aprioritization function and approaches to determine the prioritizationlevel according to at least one of the following:

An uplink transmission as indicated by a grant. In this case, theconcerned transmission may be the corresponding PUSCH transmission(typically in subframe n+4 for control signaling received in subframen), possibly at the granularity of what information is included in thesignal e.g. a PUSCH transmission may be further split as a UCIcomponent, one (or more, in case of spatial multiplexing) transportblock(s) component, and possibly also a SRS component (typically thelast symbol of the PUSCH transmission).

An uplink transmission as a consequence of a downlink assignment. Inthis case, the concerned transmission may be the corresponding HARQfeedback sent either on PUCCH or on PUSCH (typically in subframe n+4 forcontrol signaling received in subframe n), possibly at the granularityof what physical channel is used for the transmission.

A transmission for UCI, SRS or D-SR i.e. a transmission that is for HARQfeedback or for UCI (periodic or aperiodic) either on PUCCH or PUSCH, aSRS transmission (periodic or aperiodic) or scheduling request (D-SR) onPUCCH. The granularity may be at the physical channel (e.g. PUSCH,PUCCH), the type of signal (e.g. SRS, D-SR) or the type of information(e.g. HARQ feedback, CQI/PMI/RI, D-SR). For example, a WTRU may applypower scaling and to allocate lower priority to a transmission thatcontains UCI if it excludes HARQ A/N information but not otherwise.

A transmission that is part of a random access procedure (either asindicated by a DCI, or initiated autonomously by the WTRU): In thiscase, the concerned transmission may be at least one of thecorresponding initial preamble transmission, any retransmission(s) ofthe preamble and if applicable the transmission of the msg3 (includingretransmissions, if any) for a contention-based procedure.

In other words, the granularity at which the prioritization level and/orfunction may be applied can be according to at least one of thefollowing:

Initial transmission: The concerned transmission is only the initialpreamble transmission. As an example, the WTRU may determine that onlythe initial transmission of a preamble may be given a lower prioritylevel than other transmission(s) that may overlap at least partly intime with the preamble, while the WTRU may determine that anyretransmission(s) of the preamble for the concerned RACH procedure isgiven higher priority than other transmission(s) that may overlap atleast partly in time with the preamble. In this case, the WTRU may thenapply a first power allocation method (e.g. it may apply scaling of thepower, possibly even down to zero level) to the transmission of theinitial preamble when it determines that the preamble may be given lowerpriority than other transmissions (e.g. PUSCH/PUCCH), and otherwise itmay apply a second power allocation method such as a method applicablewhen the preamble does not collide with a transmission or transmissionsof another CG or such that power available to the CG (or to the WTRU)may be available for the transmission of a preamble. In some cases thismay be done only when the preamble and the other transmissions areassociated to different groups of cells (e.g. different CGs or MACinstances.)

Preamble transmission only: The concerned transmission may include anyof the preamble transmission for the concerned procedure. Possibly, thetransmission of msg3 (if applicable) may be treated as a separatetransmission from the perspective of applying a prioritization functionwhereby the WTRU may determine how to handle such transmission accordingto any approaches described herein. For example, how the WTRU receivedthe RAR (and/or its content) that includes the grant (and/or itscontent) for msg3 transmission may determine how to handle suchtransmission.

Msg3 transmission only: The concerned transmission may be only thetransmission, and retransmissions if any, of the msg3 for acontention-based procedure. For example, transmission of msg3 on PUSCHfor a serving cell of a CG may have higher priority that a transmissionon PUSCH for another CG.

Procedure-specific: The concerned transmission may include any of theuplink transmissions associated to the concerned procedure, e.g.including any preamble transmission as well as the transmission of msg3(and any retransmission, if needed).

Different granularity may be associated as a function of how the WTRUinitiates the procedure, i.e. whether the preamble transmission istriggered by the reception of a DCI on PDCCH (DL data arrival, e.g.preamble transmission only) or whether it is initiated by the WTRU(RA-SR for UL data arrival, e.g. procedure-specific).

As an example of the above method, the WTRU may assign a lower priorityto the initial transmission of a preamble than to other transmissions(e.g. PUSCH/PUCCH) only in a case where the RACH procedure was initiatedby the reception of a DCI on PDCCH, if the WTRU would be otherwisepower-limited. In some cases this may be done only if the WTRUdetermines that it may have insufficient processing time to adjust thetransmission power levels of the overlapping PUSCH/PUCCHtransmission(s). As a further example, the WTRU may scale (includingdown to zero level, or may drop) the transmission power of the initialpreamble transmission for a PDCCH-initiated RACH procedure only if thetime between the reception of the DCI and the first PRACH occasion isless than or equal to a specific amount of time (e.g. 6 ms) and if theWTRU would be otherwise power-limited due to the overlappingtransmissions.

Different granularity may be associated as a function of what MAC entityis associated with the procedure, e.g. whether the preamble transmissionis triggered for the PMAC (e.g. possibly for control plane signalingusing procedure-specific granularity) or for the SMAC (e.g. for offloaddata using preamble transmission only).

Priority may be a function of a component of a function as discussedfurther herein. In one example, the WTRU may allocate a higher priorityto one or more type(s) of transmission for a given CG as a function of asub-component of a procedure or a function.

In an example which may relate to msg3, the WTRU may allocate a higherpriority to any transmissions (e.g. including initial HARQ transmissionsand any HARQ retransmission) for PUSCH for a given CG while contentionresolution is ongoing for a contention-based random access procedure(e.g. while the contention resolution timer is running) on the uplinkresources of a serving cell of the concerned CG. The higher priority maybe allocated only for the special cell of a CG. The higher priority maybe allocated only for the PCell of the MCG. The WTRU may allocatetransmission power for transmission(s) on PUSCH up to a minimumguaranteed power, and allocate remaining power (if any) first to suchtransmissions during that period.

In an example which may relate to measurement reports, the WTRU mayallocate a higher priority to any transmissions (e.g. including initialHARQ transmissions and any HARQ retransmission) for PUSCH for themeasurement reporting procedure. For example, this may be from the timethe measurement report is triggered or submitted to lower layers fortransmission until the WTRU receives positive HARQ feedback for thecorresponding transmission. A timer may also be introduced for thispurpose. The WTRU may allocate transmission power for transmission(s) onPUSCH up to a minimum guaranteed power, and allocate remaining power (ifany) first to such transmissions during that period.

In an example which may relate to radio link problems, re-establishment,and/or radio link failure (RLF) of the secondary cell group (S-RLF), theWTRU may allocate a higher priority to any transmissions (e.g. includinginitial HARQ transmissions and any HARQ retransmission) for PUSCH whiletimer T310 (which is started when RRC receive an indication of radiolink problem from lower layers) is running. The WTRU may allocatetransmission power for transmission(s) on PUSCH up to a minimumguaranteed power, and allocate remaining power (if any) first to suchtransmissions during that period. The WTRU may perform a similarbehavior when timer T311 (which is started when the WTRU initiates theRRC Connection re-establishment procedure) is running, although analternative would be that the WTRU releases any configuration for a SCGin such case.

The following discussion relates to determination of priority as inputto a prioritization function. In one approach, the WTRU may determine apriority level (or order), and/or a prioritization function,dynamically. A WTRU may determine a priority level as a function of adynamic aspect. Such dynamic aspect may be the reception of downlinkcontrol signaling and/or the WTRUs operational state (e.g. HARQ state,whether or not a specific function e.g. SPS is activated, etc.). Suchdetermination may additionally be a function of one or moreconfiguration aspect(s). Such configuration aspect may include aconfigured grant (either for uplink transmission e.g. to determine thepriority level of a PUSCH transmission, or for downlink transmissione.g. to determine the priority level of HARQ feedback). Suchconfiguration aspect may include any parameters related to the elementslisted below, when applicable.

The WTRU may determine the priority level applicable to transmission(s)for a given TTI as a function of the received control signaling and/oroperational state of the WTRU, for example according to at least one ofthe following:

Identity of control channel (e.g. (e)PDCCH): Such priority level orprioritization function may be a function of (the identity, or type of)a control channel.

For example, the WTRU may determine that control signaling received on afirst PDCCH has higher priority level than control signaling received ona second PDCCH for a given TTI. For example, in such case, the WTRUwould give highest priority to any uplink transmission associated to anyDCI (e.g. PUSCH, PRACH, HARQ A/N on PUCCH for SPS activation,) receivedon the first PDCCH or associated to any corresponding downlinktransmissions (e.g. CSI and/or HARQ A/N on PUCCH).

For example, a grant (and/or a request) received on the PDCCH of thePCell of the primary MAC instance may have higher priority that a grant(and/or a request) received on the PDCCH of a special cell of asecondary MAC instance. For example, a grant (and/or a request) receivedon the PDCCH of a SCell of the primary MAC instance may have higherpriority that a grant (and/or a request) received on the PDCCH of aSCell of a secondary MAC instance.

For example, the WTRU may be configured explicitly such that a PDCCH mayhave an explicit priority.

For example, the WTRU may determine that control signaling received on aPDCCH has a first priority level (e.g. higher than) while controlsignaling received on ePDCCH may have a second priority level (lowerthan).

PDCCH search space: Such priority level or prioritization function maybe a function of the location of the first Control Channel Element (CCE)of the DCI that the WTRU has successfully decoded by using theapplicable RNTI (e.g. C-RNTI). For example, the WTRU may determine thatdifferent subsets of one or more CCEs represent different priority levelfor the associated DCI. The latter may be a configuration aspect of theWTRU. Possibly, such logical fragmentation of the resources of a controlchannel may be only applicable to the WTRU-specific search space(WTRUSS).

For example, the WTRU may determine the set of resources thatcorresponds to a WTRUSS for a given control channel. Additionally, theWTRU may be configured such that it may determine the starting location(first CCE) of a first subset of such WTRUSS as well as the number ofsubsequent CCE(s) (if any) that corresponds to the concerned subset. TheWTRU may determine that CCEs that are part of the concerned WTRUSS butthat are not associated to such subset represent a second subset of theWTRUSS. The WTRU may additionally determine (e.g. by configuration) thatthe first subset is associated with a first priority level and that thesecond subset is associated to a second priority level. In a subframefor which a prioritization function is applicable, the WTRU maydetermine the priority of a transmission associated with a successfullydecoded DCI as a function of the location of the DCI in the WTRUSS.

Carrier Field Indicator (CFI): Such priority level or prioritizationfunction may be a function of a field received in a DCI on a controlchannel.

For example, the WTRU may determine that control signaling received fora specific serving cell may have higher priority level than controlsignaling received for a second serving cell.

For example, the WTRU may determine that an uplink transmission for aspecific serving cell may have higher priority level than an uplinktransmission for a second serving cell.

For example, the Carrier Field Indicator (CFI) may be allocated todifferent serving cells such that a transmission associated to a cellwith lowest CFI has the highest priority level, and subsequent (inincreasing order of) CFI values are associated a lower priority level(in decreasing order of priority level).

As an example of a combination with another aspect described herein, theWTRU may determine such priority level in between cells with uplinkresources associated to a specific MAC entity by first applying thehighest levels to the MAC entity with highest priority. In particular,when the CFI space is WTRU-specific and common to all MAC entities ofthe concerned WTRU.

One possible consequence is that any cell may be configured to havehighest priority when such prioritization level is applicable, assumingthat any cell may be assigned any CFI value. Also, the PCell of theprimary MAC entity and/or the special cell of the secondary MAC entitycould be excluded from such rule or may be assigned specific prioritiesby configuration or by default.

TPC command: Such priority level or prioritization function may be afunction of a TPC command received in a DCI (from PDCCH or E-PDCCH). TheWTRU may apply a first prioritization function when the TPC commandfield has a first value and a second prioritization function when theTPC command field has a second value. For instance, the WTRU maydetermine that a transmission associated to a DCI with a specific valueof the TPC field has a higher priority level than other transmissions. Atransmission associated to a DCI may include a PUSCH in case the DCIcontains an UL grant, or of PUCCH in case the DCI contains a DLassignment. Possibly, such determination is only made if the DCI isreceived from a specific cell, or from a cell of a specific MAC instance(say a primary MAC instance). Possibly, the prioritization may beapplied to all transmissions of the MAC instance from which the DCI isreceived. Possibly, the prioritization may be applied until reception ofsignaling indicating a change of prioritization function.

In one example, reception of a TPC command field with value “3” from aprimary MAC instance may result in the determination that the associatedtransmission has highest priority and/or that power sharing between MACinstances is performed according to an absolute priority. The WTRU mayapply the TPC adjustment normally associated with the value “3”. Inanother example, no such TPC adjustment is performed.

In another example, the WTRU may interpret a TPC command as a priorityindication if such TPC command is received from a specific type of DCIor search space, such as if the TPC command is received from a DCIformat 3/3A or is received from a common search space. In this case, theWTRU may still (or not) apply a TPC adjustment as per the legacy use ofthe TPC command. Possibly, such interpretation of the TPC command in DCIformat 3/3A may be performed only if the WTRU also received at least oneTPC command in one or more DCI's in the same subframe, such as DCI'scontaining an uplink grant and/or a downlink assignment. In other words,the TPC command received in DCI format 3/3A may be interpreted as apriority indication only in case an uplink transmission (either PUCCH orPUSCH) is dynamically scheduled in the same subframe.

In another example, reception of a TPC command field with value “3” froma primary MAC instance in the DCI containing a DL assignment may resultin the determination that the number of coded symbols Q′ used for HARQA/N, in case HARQ A/N is sent over PUSCH, should be set to a highervalue maximizing the chances of successful detection at the eNB. Suchvalue may correspond, for instance, to 4 times the number ofsub-carriers of the PUSCH allocation. Alternatively, such value maycorrespond to a different (e.g. higher) value β_(offset) ^(HARQ-ACK)applicable to this case, which may be provided by higher layers.

This approach may allow, for instance, the MeNB to request that atransmission of the primary MAC instance be assigned a higher priorityto maximize chances of successful transmission of critical information.Such indication may override other prioritization rules such as thosebased on the type of transmission.

Serving Cell Index (servCell-index): such priority level orprioritization function may be a function of a configuration of theserving cell index (or identity) associated to the cell with uplinkresources associated to a given MAC entity. This may be applicable incombination with a prioritization rule between MAC instances.

For example, the WTRU may determine that control signaling received fora specific serving cell may have higher priority level than controlsignaling received for a second serving cell as a function of theassociated cell index and/or MAC entity.

For example, the WTRU may determine that an uplink transmission for aspecific serving cell may have higher priority level than an uplinktransmission for a second serving cell as a function of the associatedcell index and/or MAC entity.

For example, the serving cell index may be allocated to differentserving cells such that a transmission associated to a cell with lowestindex has the highest priority level, and subsequent (in increasingorder of) index values are associated a lower priority level (indecreasing order of priority level).

As an example of a combination with another aspect described herein, theWTRU may determine such priority level in between cells with uplinkresources associated to a specific MAC entity by first applying thehighest levels to the MAC entity with highest priority. In particular,when the serving cell index space is WTRU-specific and common to all MACentities of the concerned WTRU.

One possible consequence is that the PCell of the primary MAC instancewould have highest priority when such prioritization level isapplicable, assuming that it remains with zero value by default. If theindex of the PCell of the primary MAC instance may be configured, thenthe cell could be given flexible priority level by configuration.

Explicit indication (e.g. function/parameter set index)/flag (e.g.normal, absolute priority): such priority level or prioritizationfunction may be a function of an indication in a DCI associated with theconcerned transmission.

For example, the WTRU may receive a DCI that includes a grant for anuplink transmission and control bit(s) that indicates e.g. that thecorresponding uplink transmission has absolute/highest priority (1 bit),that it has a priority level within a given range (e.g. multiple bitsgiven the level as well as the range), that it should be handledaccording to a given prioritization function (e.g. multiple bitsindicating the function) or that it may be transmitted using analternative grant according to the indicated configuration (e.g.multiple bits indicating an index to an alternative grant).

This may be useful if control plane signaling is only transmitted in theuplink of a cell associated to a primary MAC entity (i.e. towards theMeNB), and if a WTRU is otherwise assuming that transmissions on a cellassociated to a secondary MAC entity (i.e. towards a SeNB) has higherpriority.

For example, the WTRU may receive a DCI that includes a downlinkassignment for a transmission with control bit(s) that indicates e.g.that the corresponding uplink transmission for HARQ feedback hasabsolute/highest priority (1 bit), that it has a priority level within agiven range (e.g. multiple bits given the level as well as the range),that it should be handled according to a given prioritization function(e.g. multiple bits indicating the function).

This may be useful if control plane signaling is only transmitted in thedownlink of a cell associated to a primary MAC entity (i.e. towards theMeNB), and if a WTRU is otherwise assuming that transmissions on a cellassociated to a secondary MAC entity (i.e. towards a SeNB) has higherpriority.

For the purpose of explicit indication, a new field may be defined in anew or existing DCI format. Alternatively, it may be possible tooverload an existing field, such that at least one value of suchexisting field may be interpreted as a priority indication. Forinstance, one may overload the “frequency hopping” field of DCI format 0or DCI format 4, such that a specific value of this field is interpretedas an indication of high priority. In this case the existinginterpretation of the frequency hopping field may not be followed.

In case an explicit indication (including possibly an indication from aTPC command) is received in both MAC entities in a given subframe, andboth MAC entities indicate a high priority, the WTRU may determine whichof the MAC entities will have high priority, based on a pre-definedpriority rule (e.g. primary MAC entity has priority) or another priorityrule.

Associated MAC entity (e.g. Primary, Secondary): Such priority level orprioritization function may be a function of the identity of the MACentity associated to the concerned transmission.

For example, the WTRU may receive a grant on a PDCCH that schedules anuplink transmission that is associated with a serving cell that isapplicable to a specific MAC entity (for the uplink). For suchtransmission i.e. PUSCH, the priority level may be higher for a primaryMAC entity than for other transmissions associated to a cell of anotherMAC entity.

This may be useful if only control plane signaling is transmitted in theuplink of a cell associated to a MeNB.

For example, the WTRU may determine that it should transmit a signal(e.g. HARQ feedback on PUCCH, D-SR, or a preamble) in the uplink of aserving cell, which cell is associated to a primary MAC entity. For suchsignals, the priority level may be higher for a primary MAC entity thanfor other transmissions associated to a cell of another MAC entity.

This may be useful if only control plane signaling is transmitted in thedownlink of a cell associated to a MeNB.

Type of grant (e.g. semi-persistent, dynamic, alternative grant): Suchpriority level or prioritization function may be a function of the typeof the applicable grant, for example, semi-persistent, dynamic, oralternative grant.

For example, the WTRU may give higher priority to a configured grantthan to a dynamically scheduled grant, if the grant received on thePDCCH does not otherwise override the configured grant. In other words,a priority rule may be associated to a subframe that may be periodicallyrecurring as a function of the activation of a configured grant (uplinksemi-persistent scheduling).

This could be useful to implicitly give higher priority to a SPS grantused for VoiP in the uplink of a cell of a primary MAC entity (e.g. amacro cell of the MeNB) when the WTRU receives a grant for atransmission for the secondary MAC instance (i.e. towards the SeNB).

Type of transmission (e.g. adaptive synchronous, non-adaptivesynchronous): Such priority level or prioritization function may be afunction of the type of transmission, for example, adaptive synchronousor non-adaptive synchronous.

For example, the WTRU may associate a priority level to a grant and/orto a corresponding transport block. For HARQ retransmissions for theconcerned transport block, the WTRU may determine a first priority level(e.g. a lower priority) to a WTRU-autonomous, synchronous non-adaptiveretransmission while it may determine a second priority level (e.g. ahigher priority) to a dynamically scheduled, synchronous adaptiveretransmission. Possibly, in the latter case, only if the correspondingcontrol scheduling includes an explicit indication of the prioritylevel.

This could be useful to ensure that a transmission for which a WTRU hasactually received downlink control signaling has a higher priority levelthan otherwise, e.g. in case PDCCH misdetection may be an issue (forexample, at the edge of a cell of the secondary MAC instance).

Type of HARQ transmission (e.g. initial, retransmission): Such prioritylevel or prioritization function may be a function of the HARQtransmission, for example, initial transmission or retransmission.

For example, the WTRU may associate a priority level to a HARQ processe.g. at the time of the initial transmission for the concerned HARQprocess.

Possibly, such associated priority level may be modified for the ongoingprocess as a function of another event, e.g. reception of controlsignaling for an adaptive retransmission that indicates a higherpriority level than the level determine in a previous HARQ transmissionfor the concerned process. For example, the WTRU may determine that agrant for an initial HARQ transmission for a first transport block maybe given a higher priority level than e.g. a grant for an adaptiveretransmission or a non-adaptive retransmission for a second transportblock, possibly for which the corresponding initial transmission had alower priority level. For example, the WTRU may determine the relativepriority level between a grant for an initial HARQ transmission and aHARQ retransmission by comparing the priority level of the correspondinginitial transmission for the respective ongoing HARQ process.

As another example, the WTRU may determine that the priority levelassociated with the previous transmission for a given HARQ process isextended to the next HARQ transmission for the same transport block,unless the WTRU determines that a different priority level should beapplied (e.g. according to any of the approaches described herein).

In an example approach, in case of resegmentation for a retransmission,the extension of the priority may apply to any transmission that maycontain a segment of the data included in the resegmented transmissionunit.

This could be useful to ensure that a transmission that initiallybenefits from some priority can continue with such priority until iteither succeeds or fail in either the DL offload or the DL throughputcases.

HARQ process identity (e.g. range of TTIs, ongoing process): Suchpriority level or prioritization function may be a function of thetiming of the HARQ process that handles the transmission.

For example, the WTRU may implement rules such that in a given (possiblyconfigurable) set of TTIs (e.g. first TTI of a radio frame or subframe#0) any uplink transmission(s) associated to the primary MAC entity isassociated to a higher priority level while for a second set (possiblyconfigurable) of TTIs (e.g. the other TTIs in the radio frame orsubframe #1-#9) any uplink transmission(s) associated to the secondaryMAC entity is associated to a lower priority level. Possibly, in theconfiguration, all subframes may refer to timing associated to a singleMAC entity.

Alternatively, the WTRU may receive control signaling that sets aspecific priority to a given HARQ process and/or TTI. Such controlsignaling may activate such priority. Such priority may be time-limitedsuch as until the WTRU receives further control signaling thatdeactivates the non-default priority. Possibly, such signaling may onlybe applicable to a single MAC entity (e.g. it may be controlled by asingle eNB).

Number of transmission for the concerned HARQ process (threshold): Suchpriority level or prioritization function may be a function of thenumber of transmissions for a HARQ process.

For example, the WTRU may determine that for a given HARQ process, ifthe number of HARQ transmissions reaches the maximum number of HARQtransmissions minus X (where X may be a configuration aspect), the WTRUmay determine that any subsequent transmission(s) for the concerned HARQprocess may have a higher priority level. Possibly, only if one or moreprioritization functions have been applied to at least one transmissionfor this HARQ process. Possibly, only for a subset of the HARQprocesses, which subset may be a configuration aspect of the WTRU. Inother words, some (or all) HARQ processes may be configured such thatthe priority level associated to the corresponding transmission may varyas the number of retransmissions increase. Possibly, this may beconfigured per serving cell, of for all cells of a given MAC entity, orfor all cells of the WTRU's configuration.

Redundancy version (RV) for the HARQ transmission (e.g. 0-4): Similarlyas for the number of transmission for the HARQ process as describedabove, such priority level or prioritization function may be a functionof the RV applicable for the concerned transmissions. For example, theWTRU may determine that the priority level of a transmission increasesas it cycles through the sequence of RV for each HARQ transmissions.Alternatively, a specific priority may be associated to a specificredundancy version index.

Type of data/signal for the transmission (UP/CP vs UCI, HARQ A/N vs D-SRvs SRS, PMI/CQI/RI): Such priority level or prioritization function maybe a function of the type of data that is included in the concernedtransmission. For example, the WTRU may determine that a transmissionthat includes control plane data (i.e. from SRB) has higher prioritythan a transmission of user plane data (e.g. for either a primary or asecondary MAC entity) or than transmission of HARQ A/N feedback on PUCCH(e.g. for a secondary MAC entity).

Such priority level or prioritization function may be a function of thetype of signal for the concerned transmission. For example, the WTRU maydetermine that a transmission for HARQ A/N feedback (either on PUCCH oron PUSCH) has higher priority than any other transmissions.

For example, the WTRU may determine that the priority levels areaccording to the following (in decreasing priority order):

-   -   PUCCH that includes HARQ A/N feedback;    -   PUSCH that includes HARQ A/N feedback;    -   PUSCH that includes control plane signaling;    -   Preamble on PRACH;    -   PUCCH that includes SR;    -   UCI on PUCCH;    -   UCI on PUSCH;    -   PUSCH that includes user plane data;    -   SRS.

As an example of a combination with another approach herein, the WTRUmay determine that the priority levels are according to the following(in decreasing priority order):

-   -   PUCCH that includes HARQ A/N feedback, for PCell of Primary MAC        entity;    -   PUSCH that includes HARQ A/N feedback, for PCell of Primary MAC        entity;    -   PUSCH that includes control plane signaling, for PCell of        Primary MAC entity;    -   Preamble on PRACH, for PCell of Primary MAC entity;    -   HARQ A/N and/or UCI on PUCCH, Secondary MAC entity;    -   HARQ A/N and/or UCI on PUSCH, Secondary MAC entity;    -   PUSCH that includes user plane data, for any cell of the        Secondary MAC entity;    -   Preamble on PRACH, for any cell of Secondary MAC entity;    -   PUSCH that includes user plane data, for any cell of the Primary        MAC entity;    -   Any other type of transmissions (e.g. UCI, SRS) on any        configured serving cell.

Type of data in the transport block for the transmission (RRC/NAS PDU,RRC procedure, SRB vs DRB, RB_id): Such priority level or prioritizationfunction may be a function of the type of bearer that is associated withthe data included in the uplink transmission.

For example, the WTRU may determine that a transmission associated tocontrol plane data, e.g. for transport blocks that include data from aSRB, has a higher priority level than any user plane data.

This could be useful to ensure that control plane signaling always havepriority in any scenario.

RNTI used to decode DCI (e.g. first and second RNTI have differentpriority levels: Such priority level or prioritization function may be afunction of the RNTI used to successfully decode a DCI on PDCCH. Forexample, the WTRU may attempt to decode DCIs using a plurality of RNTIs(possibly configured) such that a first RNTI indicates a higher prioritylevel while a second DCI indicates a lower priority level. In anotherpossibility, a standalone priority indication may be included in a newor modified DCI format decoded with a specific RNTI.

Aggregation level (e.g. AL8 may indicate higher priority level): Suchpriority level or prioritization function may be a function of theaggregation level associated to a successfully decoded DCI on PDCCH. Forexample, the WTRU may determine that a DCI decoded with the highestapplicable AL indicates a higher priority level while other AL indicatesa lower priority level.

Type of physical channel/signal (PUCCH vs PUSCH, SRS, D-SR, PRACH): Suchpriority level or prioritization function may be a function of the typeof physical channel associated with the transmission. For example, theWTRU may determine that any PUCCH transmission has higher priority levelthan other types of transmissions. For example, the WTRU may determinethat any SRS transmission has a lower priority level.

Type of trigger that initiated the transmission: Such priority level orprioritization function may be a function of the event following whichthe WTRU has initiated the transmission.

For example, the WTRU may determine that the transmission (orretransmission) of a first preamble associated to a contention-freerandom access procedure (e.g. such as initiated from the reception of aDCI from the network) has higher priority than the transmission of asecond preamble associated to a contention-based random access procedure(e.g. such as initiated autonomously by the WTRU from a schedulingrequest). In such case, the WTRU may determine that it should performthe transmission of the first preamble according to any applicablecontrol information, while the transmission of the second preamble maybe postponed to a subsequent PRACH occasion.

Determination that scaling would be required: Such priority level orprioritization function may be a function of whether power scaling wouldneed to be applied or not applied based on the selected transmission.For instance, a WTRU may determine that scaling may be applied on aPUSCH transmission containing UCI or a specific type of UCI (e.g. HARQA/N) in a certain subframe. In this case, the WTRU may determine thatsuch UCI or HARQ A/N is transmitted over PUCCH instead of PUSCH, anddrop the PUSCH transmission. Possibly, such determination may be subjectto the additional condition that the WTRU determines that scaling wouldnot need to be applied on the PUCCH transmission. The PUCCH resourceused in this case may be the resource tied to the DL assignmentaccording to existing rules for the case of no PUSCH transmission.

Amount of power backoff required (MPR, A-MPR): Such priority level orprioritization function may be based on the amount of power backoffrequired. For example, the WTRU may determine that a certain amount ofpower backoff (e.g. MPR) is required for transmissions associated to afirst MAC entity and another amount for transmissions associated to asecond MAC entity; it may determine to prioritize transmission(s)associated to the MAC entity that requires the largest amount. Possibly,only if the resulting power allocated is above a certain threshold.

Furthermore, it should be noted that such priority level may be afunction of any combination of the above.

In one approach, the WTRU may determine the priority level orprioritization function applicable to transmission(s) for a given TTI asa function of configurable rules.

In one approach, the WTRU may be configured with a (possiblysemi-static) priority for uplink transmissions. Such priority may beapplicable for uplink transmissions between different MAC instances. Forexample, the WTRU may be configured such that in a given transmissiontime interval (TTI), the WTRU always prioritizes an uplink transmissionassociated to the Uu interface of the MeNB (herein referred to as theprimary MAC entity). For example, such priority may be configured byphysical channel type (e.g. PUSCH, PUCCH, PRACH), signal type (e.g.SRS), type of content in a transport block (e.g. SRB, DRB), by subframeconfiguration, or the like (similarly as for elements described indynamic rules below).

For example, a WTRU may be configured such that any uplink transmissionassociated to a primary MAC entity has higher priority than thoseassociated to a secondary MAC instance. This could be useful in a DLoffload scenario where only control plane data is being scheduled by theMeNB using the primary instance.

For example, a WTRU may be configured such that any uplink transmissionassociated to a SRB has higher priority than those associated to a DRB.This could be useful in a UL/DL throughput scenario.

For example, a WTRU may be configured such that any uplink transmissionassociated to a SRB has higher priority than those associated to anyDRB, while any uplink transmission associated to a DRB of a secondaryMAC entity and which DRB is only associated to the secondary MAC entityhas higher priority than other DRB(s).

This could be useful in a DL throughput scenario with L2 architecture 1Asuch that starvation may be avoided for such DRB. A MeNB that determinesthat DL throughput is impacted possibly from such prioritization mayreconfigure the WTRU accordingly (the converse may not be possible).

Static rules are described further herein.

In one approach, the WTRU may determine the priority level orprioritization function applicable to transmission(s) for a given TTI asa function of pre-defined rules.

For example, the WTRU may allocate a higher priority to thetransmissions of a HARQ process associated with a configured grant thanto a transmission associated to another process. For example, the WTRUmay perform power scaling such that a PUSCH transmission that isdynamically scheduled for a HARQ process that is not associated with aconfigured grant is allocated power after a process with a configuredgrant (whether or not the transmission is adaptive).

For example, the WTRU may allocate a higher priority to thetransmissions of HARQ feedback for a HARQ process associated with aconfigured assignment than to a transmission associated to another HARQprocess. For example, the WTRU may perform power scaling such that atransmission that includes HARQ feedback for a HARQ process that is notassociated with a configured grant is allocated power after atransmission that includes HARQ feedback for a process with a configuredassignment (whether or not the downlink transmission was adaptive).

Precedence between priority rules and prioritization functions isdescribed further herein.

In case it is not possible to differentiate between two transmissionsaccording to a first priority rule, a second priority rule may beutilized to determine which of the two transmissions is prioritized,according to a pre-determined precedence order between priority rules.For instance, a first priority rule may be to prioritize a transmissionthat includes HARQ A/N feedback. In case two transmissions carry HARQA/N feedback, the prioritized transmission may be determined accordingto a second priority rule which may be to prioritize a transmissionassociated to a primary MAC entity over a transmission associated to asecondary MAC entity. In the above case the priority rule based oncarrying of HARQ A/N feedback has precedence over the priority rulebased on associated MAC instance. It would also be possible that thepriority is determined first based on associated MAC instance, and onlyif the associated MAC instance is the same the priority is thendetermined according to whether the transmissions carry HARQ A/N.

In one example, a first priority rule may be based on a type oftransmission and/or type of UCI, such as whether a transmission carriesHARQ A/N in PUCCH or PUSCH. In case two transmissions from different MACinstances (or cell groups) have equal priority with respect to the firstpriority rule (e.g. both carry HARQ A/N, or both carry HARQ A/N over thesame physical channel), the prioritized transmission may be selectedaccording to at least one of:

-   -   a. Signaling or configuration from the network. For instance,        the WTRU may be receive an indication from higher layers of        which cell group's transmission is prioritized in this case. In        another example, the WTRU may determine the priority based on a        downlink control information field associated to one of the        transmissions. For instance, the WTRU may prioritize a        transmission of a primary MAC instance (MCG) if the TPC field of        the associated grant or assignment indicates an increase of        power, and a secondary MAC instance (SCG) otherwise.    -   b. The values of other parameters that may be related to power        prioritization. For instance, the transmission selected for        prioritization may be the one associated to the cell group for        which the highest, or the lowest, amount of guaranteed power is        configured. In another example, the transmission selected for        prioritization may be the one taking place on the serving cell        which has the lowest (or highest) cell identity (PCI), the        lowest (or highest) serving cell identity, or the lowest (or        highest) frequency (or E-ARFCN).    -   c. The amount of UCI information bits in the transmission (CSI        and/or HARQ-A/N information).    -   d. The transmission timing. For instance, the WTRU may        prioritize the earliest (or the latest) between the two        transmissions.    -   e. A function of at least one amount of power that may be        associated to the transmissions to be prioritized, in absolute        units (linear) or relative to a configured maximum power, such        as an amount of desired (or required) power, a portion of power        allocated from the guaranteed power, a portion of the        non-guaranteed power that is still available, or an amount of        power that would be allocated if a transmission would be        prioritized. For instance, the following quantities could be        used:        -   i. The difference between the desired power and the            allocated power for each transmission (i.e., the “missing            power”), either in linear or in dB terms, that would exist            assuming that one transmission was prioritized over the            other. For instance, the WTRU may select the transmission            such that the minimum value between the missing powers is            the smallest possible, thus maximizing the probability that            at least one transmission is successful. For instance, if            the missing powers of both transmissions would be 0 dB and 3            dB if a first transmission would be prioritized, and the            missing powers would be 1 dB and 1.5 dB if a second            transmission would be prioritized, the WTRU may determine            that the first transmission is prioritized. Alternatively,            the WTRU may select the transmission such that the maximum            value between the missing powers is the smallest possible.            Using the same example as above, the WTRU would then            determine that the second transmission is prioritized.        -   ii. The amount of desired power of the transmission,            possibly net of any portion already allocated from a            guaranteed power. For instance, the WTRU may prioritize the            transmission for which the desired power is the smallest (or            the largest).

In another example, a first prioritization function, such as MAC sharingbased on guaranteed available power, may be applied only in a case wherethe same priority (e.g. between MAC instances) is determined accordingto a second prioritization function. For instance, the secondprioritization function may determine priority based on whether a HARQA/N is included in a transmission of a MAC instance.

Additional power headroom report (PHR) triggers are discussed furtherherein.

In an example approach, PHR may be triggered as a consequence ofinsufficient transmit power resulting from concurrent scheduling.

More specifically, the WTRU may trigger a PHR if it determines that ithas insufficient available power. Possibly, the WTRU may trigger a PHRonly if the WTRU performs transmissions that at least partly overlapbetween two subset of transmissions, e.g. between transmissionsassociated to different CGs. Possibly, the WTRU may trigger a PHR onlyif such transmissions correspond to the same subframe in both CGs.

PHR trigger condition may be based on insufficient available power ordue to scaling event: The WTRU may trigger the PHR if it determines thatit should perform scaling of power to at least one transmission.Possibly, the WTRU only triggers PHR where such scaling is performed ifthe WTRU performs transmissions that at least partly overlap between twosubset of transmissions, e.g. between transmissions associated todifferent CGs. Possibly, the WTRU may trigger a PHR only if suchtransmissions correspond to the same subframe in both CGs. Possibly, theWTRU may trigger a PHR only if scaling occurs because the WTRU wouldhave otherwise exceeded the total available transmission power for theWTRU.

The terms “Scaling event” or “determination of insufficient power” maybe used interchangeably in methods below: In the description of methodsbelow either a scaling event or determination that power is insufficientmay be used interchangeably. When a method refers to a scaling event, itis understood that the method is equally applicable to a trigger basedon determination that power is insufficient, and vice-versa. It isunderstood that those methods may be also equally applicable with anyother prioritization function described herein. Methods described hereinmay be used by themselves or in different combinations.

Trigger may be conditional to the definition of insufficient power—e.g.total WTRU power is exceeded: In one method, the WTRU may trigger suchPHR only if it determines that the required transmission power for alltransmissions of the WTRU for the concerned subframe exceeds the totalWTRU available power.

Example with P_MeNB and P_SeNB has maximum power per CG: For example,the WTRU may be configured with a maximum transmit power for differentsubsets of transmissions (or cells) i.e. the WTRU has a maximumavailable transmission power per CG. The sum of the maximum allocatedfor each may exceed the total available WTRU power. In this case, theWTRU may trigger a PHR only if the power required in each subset doesnot exceed its maximum allocation but the sum of the required poweracross all transmissions of the WTRU exceeds the total available WTRUpower. In other words, the WTRU may have insufficient power to allocateto a subset of transmissions (e.g. power available per CG may beinsufficient) but the WTRU may not trigger a PHR if the total WTRUavailable power is not exceeded.

Example with P_MeNB (and optionally P_SeNB) as minimum guaranteed powerper CG: For example, the WTRU may be configured with a minimumguaranteed power for at least one subset of transmissions (or cells)i.e. the WTRU may have a minimum guaranteed available transmission powerfor at least one CG. In this case, the WTRU may trigger a PHR only ifthe sum of the required power across all transmissions of the WTRUexceeds the total available WTRU power.

A PHR trigger may be conditional to specific criterion that increasedthe power requirement—e.g. scheduling. In one method, a PHR may betriggered if power-limited/scaling occurs and a power requirementincreases.

The WTRU may trigger a PHR only on a condition that it determines thatit has insufficient available power (or that power scaling was applied)due to an increase in the required power for at least one CG.

For example, the WTRU may determine that the increase in powerrequirement for a CG is mainly due to scheduling requirement fromcontrol signaling received for the concerned CG, and not mainly due to achange in pathloss (e.g. the change in pathloss estimation did notexceed a threshold e.g. similar to the condition for the PHR trigger dueto change in pathloss). For example, the WTRU may be scheduled fortransmissions with increased number of PRBs, such that power requirementis exceeded for the WTRU at least in part due to such increase.

PHR triggered if a power requirement increases by a certain amount: Forexample, the WTRU may determine that the power requirement of a CG hasincreased by a certain amount. The WTRU may consider the difference inpower used from one subframe to another, or over a certain period (e.g.using a window-based mechanism) during which the WTRU is scheduled fortransmissions in the CG. For instance, the WTRU may consider an averageover the window or a maximum value over the window. Possibly, the periodmay correspond to the period since the last time PHR was triggered ortransmitted, or alternatively a period corresponding to the last Nsubframes where N may be fixed or configured. Possibly, the WTRU mayonly consider subframes in which it performs transmissions. Possibly,only for such subframes in which the WTRU is scheduled for transmissionsin both CG. The threshold used by the WTRU to determine that power for aCG has increased such that the WTRU should trigger a PHR may be aconfiguration aspect of the WTRU. The reference value for the increasemay correspond to the value at the time PHR was last triggered or waslast reported, or may be a configured value.

PHR triggered if a power requirement increases to a certain level: Forexample, the WTRU may determine that the power requirement of a CG hasincreased beyond a certain value in a given subframe or during a certainperiod (e.g. by tracking power using a moving average). Possibly, theWTRU may only consider subframes in which it performs transmissions.Possibly, only for such subframes in which the WTRU is scheduled fortransmissions in both CG. Possibly, the threshold used by the WTRU mayalso be a configurable aspect. Possibly, the threshold used by the WTRUmay correspond to the amount of reserved power for the concerned CG e.g.the WTRU triggers such PHR when it determines that the power requirementfor the CG exceeds the minimum guaranteed power for the CG.

Methods for determining an increase in power requirements or powerrequirement level: Possibly, for any of the above, the WTRU may consideronly the power allocated to transmission(s) associated to a subset oftransmissions, such as transmissions of a certain physical channel orsignal or for certain serving cells. For instance, the WTRU may considerPUSCH transmissions only, or PUSCH and PUCCH transmissions only.Possibly, for any of the above, the WTRU may consider only the powerallocated to transmission(s) that are dynamically scheduled. Possibly,for any of the above, the WTRU may consider an increase in powerrequirement based on the amount of increase in total bandwidth (ornumber of resource blocks), for PUSCH transmissions, or in a factorrelated to the modulation and coding (Delta_TF) or format of the PUSCHor PUCCH transmission, or a factor related to a TPC command (oraccumulation thereof) for the PUSCH or PUCCH transmission. Possibly, forany of the above, the WTRU may consider an increase in power requirementbased on an increase of downlink path loss estimate. The WTRU mayconsider a potential increase in power requirement based on an increaseof configured maximum power per cell or a configured maximum power percell group. Possibly, for any of the above, the WTRU may determine apower requirement based on a power headroom or a virtual power headroom,and correspondingly consider an increase in power requirement based on areduction in power headroom or a reduction in virtual power headroom.

For any of the above, the WTRU may consider the total power requirementsfrom transmissions of all serving cells of the CG. Alternatively, theWTRU may consider the power requirements from each cell of the CGseparately and trigger PHR if the condition is met for at least one ofthe cells. Alternatively, the WTRU may consider an average powerrequirement.

PHR may be triggered from decrease in power requirement: In somesolutions, the WTRU may trigger PHR if the power requirement of a CG hasdecreased by a certain amount. The WTRU may use any metrics or criteriadescribed herein for determining the power requirement, however thetrigger may occur upon a determination of decrease of power requirementinstead of an increase. If the power requirement of the cell group isdetermined from power headroom, the trigger may then occur when thepower headroom increases.

PHR is triggered as a function of the amount of scaling applied, oramount by which available power is exceeded: Possibly, the WTRU maytrigger such PHR only if the amount of scaling applied exceeds aspecific value.

PHR may be triggered only if the power situation is non-transient:Possibly, the WTRU may trigger such PHR only if scaling has occurred (orif power has been insufficient) for a certain period of time thatexceeds a specific amount of time, or for a number of subframes in whichthe WTRU had overlapping transmissions that exceed a specific number ofsubframes, i.e. such that the condition for triggering the PHR is nottransient but persistent. Such specific value may be either specified orconfigured (e.g. using a timer). Such value may be set to 1 subframe (or1 ms) such that a single event may trigger the PHR, or set to 0 todisable such PHR trigger. The WTRU's count in this case may be reset forany transmission of a PHR (or for any trigger) for the concerned CG(s).

PHR may be triggered to both CGs, or a single CG: Possibly, a PHR istriggered for both CGs. Possibly, the WTRU may perform additionalprocessing to determine whether a PHR is triggered towards one CG onlyor both. For example, the WTRU may trigger a PHR for both CG as a resultof any type of scaling event. For example, the WTRU may trigger a PHRfor a second CG when it scales the power (possibly even down to 0) of atleast one transmission associated to a first CG. For example, the WTRUmay trigger a PHR for both CGs when it scales the power (possibly evendown to 0) of at least one transmission associated to each CG. Possibly,if the WTRU determines that scaling was applied due to an increase inpower required for transmissions for one CG, the WTRU triggers the PHRonly for that CG. For all cases, optionally the WTRU may trigger the PHRfor the concerned CG only if the associated prohibit timer is notrunning. A prohibit timer may be associated to a specific PHR typeand/or trigger.

The PHR trigger may be cancelled once a PHR is transmitted. Possibly,such trigger may be cancelled earlier if the WTRU determines in asubframe subsequent to the one that triggered the PHR that the conditionthat triggered the PHR is no longer met, e.g. that power scaling is notapplied while both CGs are performing uplink transmissions that overlap,and possibly only if there is at least one PUSCH transmission for eachCG in the concerned subframe.

Possibly, PHR is triggered as a consequence of insufficient transmitpower resulting from concurrent scheduling only if WTRU functionality isimpacted negatively.

The WTRU may apply a prioritization function such that the resultingoutcome impairs the WTRU from performing another function.

In an example approach, PHR may be triggered in a second MAC entityfollowing SR failure in first MAC entity.

For example, such function may be one of a scheduling request e.g.transmission of SR on PUCCH failed and at least one of: the WTRU hasscaled the transmission power for at least one of the transmissionattempt(s) and/or dropped the transmission. Alternatively, it may be anySR including one performed using random access (RACH).

In an example approach, PHR may be triggered in a second MAC entityfollowing HARQ failure in first MAC entity.

For example, such function may be a HARQ process that reaches maximumnumber of transmissions (i.e. the process is unsuccessful) and at leastone of: the WTRU has scaled the transmission power for at least one ofthe transmission attempt(s) and/or has dropped at least one of itsassociated (re)transmissions and/or has used an alternative grant forthe transmission of a TB.

In an example approach, PHR may be triggered in a second MAC entityfollowing a determination that QoS not met in first MAC entity.

For example, such function may be a Logical Channel Prioritizationprocedure that fails to meet the required prioritized bitrate and atleast one of: the WTRU has scaled the transmission power for at leastone of the transmission attempt(s) and/or has dropped at least one ofits associated (re)transmissions and/or has used an alternative grantfor the transmission of a TB. Possibly, over certain period of time e.g.integer multiple of a bucket delay.

For example, such function may be the discarding of at least one PDCPSDU due to the expiration of the associated PDCP Discard Timer and atleast one of: the WTRU has scaled the transmission power for at leastone of the transmission attempt(s) and/or has dropped at least one ofits associated (re)transmissions and/or has used an alternative grantfor the transmission of a TB. Possibly, when a certain number of SDUshave been discarded over a specific period of time.

For example, such function may be the state of the WTRU's buffers, suchas when the head of queue delay (or when the oldest SDU in the PDCPbuffer) becomes larger than a specific threshold. This may be based onthe SDU Discard Timer reaching a specific value. In another approach,this may be based on the average value of the SDU Discard Timer at thetime where the SDU is removed from the queue (including due tosuccessful transmission and due to discard events) and maintained forall SDUs in the WTRU's buffer; the WTRU may determine that furtheraction(s) is needed when such average exceeds a specific threshold (e.g.the time of stay in the WTRU's buffer is generally increasing beyond acertain limit). Possibly, when computer over a specific period of time.Possibly, when combined with at least one of: the WTRU has scaled thetransmission power for at least one of the transmission attempt(s)and/or has dropped at least one of its associated (re)transmissionsand/or has used an alternative grant for the transmission of a TB.

For example, such function may be the state of the WTRU's buffers, forexample where the amount of data in the WTRU's buffer becomes largerthan a specific threshold. This may be based on the reported BSRreaching a specific value (possibly in terms of the sum for allconfigured LCGs). In another approach, this may be based on the rate atwhich the data accumulates in the WTRU's buffer is generally increasingbeyond a certain limit). Possibly, when computer over a specific periodof time. Possibly, when combined with at least one of: the WTRU hasscaled the transmission power for at least one of the transmissionattempt(s) and/or has dropped at least one of its associated(re)transmissions and/or has used an alternative grant for thetransmission of a TB.

In an example approach, PHR may be triggered upon change ofprioritization function or associated parameters. For example, the WTRUmay receive physical layer, MAC signaling or RRC signaling indicating achange of parameter(s) affecting power sharing between MAC instances,such as a set of guaranteed available power(s) for at least one MACinstance. In another example, the WTRU may receive signaling indicatinga change of prioritization function, such as from power sharing betweenMAC instances performed according to an absolute priority to powersharing between MAC instances performed based on a guaranteed availablepower, or vice versa. In another example, the WTRU may reduce orincrease a guaranteed available power for at least one MAC instance as aresult of determining that at least one bearer does not meet a QoScriterion, as described herein (PHR may be triggered upon change ofpriority between MAC instances and scaling may be applied.)

In an example approach, PHR may be triggered upon change of prioritybetween MAC entity and with the condition that the WTRU applies aprioritization function. For example, the WTRU may receive physicallayer signaling or MAC signaling indicating a change of parameter(s)affecting power sharing between MAC instances, such that absolutepriority is assigned to a specific MAC instance. The WTRU may trigger aPHR if a prioritization function is required such that power scaling isapplied to the MAC instance with lower priority in the first TTIsubsequent to the reception of the control signaling in which the WTRUperforms at least one transmission associated to each MAC instances.Possibly, the WTRU triggers the PHR in the TTI corresponding to theconcerned transmissions.

In another example, the WTRU may reduce or increase a guaranteedavailable power for at least one MAC instance as a result of determiningthat at least one bearer does not meet a QoS criterion, as describedherein above.

In an example approach, triggered reporting may include a PHR report, orsomething else e.g. QoS satisfaction, UL Radio Link Problems, etc.

In any of the cases above, the WTRU may initiate a procedure thatreports some state to an eNB.

For example, the WTRU may trigger a PHR in a second MAC entity if theWTRU determines that at least one of the above events has occurred for afirst MAC entity.

For example, the WTRU may trigger a PHR report for each of theconfigured MAC entities when it receives a first grant following theinitial configuration of a secondary MAC entity. In one approach, theWTRU may transmit a PHR report that includes a PH value computed basedon all the transmission(s) performed in the TTI corresponding to thetransmission of the PHR (i.e. using all received grants). Possibly, onlyif the WTRU performs at least one transmission associated to each of theconfigured MAC entities. In one approach, the WTRU may transmit a PHRreport that includes PH value(s) computed according to legacy approachesfor the concerned first MAC entity (the one associated with thetransmission of the concerned PHR) and that additionally includes PHvalue(s) for a second MAC entity which values are computed using apseudo grant. Such grant may be a grant equivalent to the one used forthe transmission of the PHR, or a predefined grant. Possibly, the sameapproach may be applied for the PHR associated to the second MAC entity.For the latter case, the PHR is transmitted according to the principlewhere (the WTRU reports its power situation if the same grant was usedin the same time instant for transmissions towards each eNB).

PHR reporting—When to transmit PHR may be a function of the type oftrigger: In legacy systems, where a PHR is triggered the WTRU mayinclude a PHR in the first subfame for which the WTRU has uplinkresources available for a transmission. With dual connectivity, where aPHR is triggered, the WTRU may determine that the PHR may be transmittedin a given subframe using more specific rules.

In one approach, the WTRU may determine in what subframe (or using whatuplink resources) it should include a PHR for a given trigger as afunction of the type of event that triggered the PHR (or PHR trigger).For example, if the event that triggered the PHR is related to a changein the power situation of the WTRU that may affect the power situationonly for transmissions in a single CG then the WTRU may include a PHR inthe first subframe for which it only has uplink resources fortransmission(s) in that CG (hereafter a “CG-specific PHR trigger”);otherwise, it may include a PHR only in the first subframe for which ithas uplink transmissions in both CGs (hereafter a “WTRU-specific PHRtrigger”). Examples of events that may be considered to affect the powersituation for both CGs include a configuration received by the WTRU thatmodifies PHR reporting for both CG (e.g. such that PHR reporting isenabled for both), a configuration that modifies the prioritizationfunction (e.g. a function for sharing power between CGs changing betweensemi-static power split and dynamic power sharing) and/or one or moreparameters of the prioritization function used for power sharing betweenCGs (e.g. P_MeNB, P_SeNB), determination of a change in thesynchronization between CGs (a change between synchronized andasynchronous) and the like. Examples of events that may be considered toaffect the power situation of a single CG include a configurationreceived by the WTRU that modifies PHR reporting for that CG (such thatPHR reporting is enabled or reconfigured, and not disabled), a change inactivation state for one or more SCell(s) of the CG with configureduplink, the expiration of a CG-specific periodicPHR-Timer, a change inthe path loss for at least one cell of the CG e.g. that triggers a PHRfor the CG, and the like.

If multiple PHR triggers occur before any PHR can first be transmitted,and if at least one is of the “CG-specific PHR trigger” type and atleast one is of the “WTRU-specific PHR trigger” type, the WTRU mayperform at least one of the following: The WTRU may include a PHRaccording to logic associated to each PHR trigger, e.g. which may resultin PHR being included in multiple transmissions across more than onesubframe. For example, in this case the WTRU may perform PHR reportingin the first subframe for which it only allocate power for transmissionsassociated to a single CG (possibly, once for each CG in case there isat least one CG-specific trigger for each CG) and also for in the firstsubframe for which it allocates power for at least one transmission foreach CGs. In this case, the result may be that the WTRU would transmitPHR for the CG-specific trigger with value(s) associated to the CG onlyas well as associated with both CGs by considering “virtualtransmission” parameters for the other CG, while the WTRU would transmitPHR for the WTRU-specific trigger with value(s) associated to actualtransmissions in each CG. The WTRU may include a PHR according to logicapplicable to the first subframe for which the WTRU has uplink resourcesavailable for transmissions. For example, in this case the WTRU wouldperform PHR reporting according to the CG-specific trigger if the firstsubframe with available uplink resources for transmissions is fortransmission(s) a single CG. For example, in this case the WTRU wouldperform PHR reporting according to the WTRU-specific trigger if thefirst subframe with available uplink resources for transmissions is forat least one transmission for each CG.

Prohibit timer for PHR type: The WTRU may support different PHR types(e.g. formats). For example, one format may be used to report powerinformation related to scheduling in a single CG while another formatmay be used to report power information related to concurrent schedulingin more than one CG. For each type, a different trigger may be defined.

Possibly, the WTRU may be configured with a prohibit timer (e.g. tolimit the frequency of the reporting mechanism) for a specific type ofPHR. For example, the WTRU may be configured to report PHR forconcurrent scheduling in more than one CG at most once per specificperiod, or alternatively using a different restriction period than foranother PHR type.

Periodic by PHR type: The WTRU may be configured to periodically reportPHR for a specific type. For example, the WTRU may be configured toreport PHR for concurrent scheduling in more than one CG only, oralternatively using a different period than for another PHR type.

Reporting QoS not met: In an example, the WTRU may trigger a reportrelated to QoS state for the concerned MAC entity (e.g. the victim MACentity for which one or more function(s) has not been successful). Suchreport may be transmitted using resources associated to a second MACentity (e.g. the MAC entity).

In an example, a WTRU may initiate a notification procedure For example,the WTRU may trigger a L3 notification procedure.

Another possible approach to handle D-SR is to not increment the SRcount is the transmission of SR on PUCCH may not be performed, e.g.according to the following:

For this MAC entity, as long as one SR is pending, the WTRU shall foreach TTI:

-   -   if no UL-SCH resources are available for a transmission in this        TTI:    -   if the WTRU has no valid PUCCH resource for SR configured in any        TTI: initiate a Random Access procedure (see subclause 5.1) on        the PCell and cancel all pending SRs;    -   else if the WTRU has a valid PUCCH resource for SR configured        for this TTI and if this TTI is not part of a measurement gap        and if sr-ProhibitTimer is not running:    -   if SR_COUNTER<dsr-TransMax:    -   increment SR_COUNTER by 1;    -   instruct the physical layer to signal the SR on PUCCH;    -   if the WTRU can allocate sufficient power for the transmission        of SR on PUCCH in this TTI:    -   increment SR_COUNTER by 1;    -   start the sr-ProhibitTimer.    -   else:    -   notify RRC to release PUCCH/SRS for all serving cells;    -   clear any configured downlink assignments and uplink grants;    -   initiate a Random Access procedure (see subclause 5.1) on the        PCell and cancel all pending SRs.

Possibly, the above approach may be bounded in time. For example, theWTRU may delay a D-SR transmission due to insufficient available poweronly up to a maximum amount of time. The WTRU may thus additionallyconsider that it has reached the maximum amount of D-SR transmissionattempts when the delay reaches or exceeds such maximum.

The following discussion relates to uplink control informationtransmission approaches. In some approaches, transmission of UCI, or ofcertain type of UCI such as HARQ, CSI or SR may be restricted to asubset of subframes for a given MAC instance. Furthermore, the subsetsof subframes may be configured such that there is never simultaneoustransmission of UCI in two MAC instances, as will be shown in examplesbelow. The restriction may apply only to UCI, or to a subset of UCI(such as HARQ), while not applying to other types of uplinktransmissions such as PUSCH without UCI. Alternatively the restrictionmay apply to all types of uplink transmissions. This approach has thebenefit of preventing scaling down the transmission power of UCI for one(or both) of the MAC instances when the maximum configured transmissionpower would be exceeded in a subframe. The approach may be combined withapproaches for prioritization wherein transmissions carrying UCI orcertain types of UCI are prioritized over transmissions not carryingUCI, possibly irrespective of which MAC instance they pertain to. Therestriction may be applied for either FDD or TDD, with differentconfigurations.

When a restriction is configured on UCI transmission for a MAC instance,the timeline of HARQ feedback with respect to the PDSCH transmission forwhich feedback is provided may be modified to allow for continuoustransmission in the DL. This is demonstrated in the following exampleapproaches.

In one example approach (for FDD), HARQ feedback may be restricted to 4out of 10 subframes for a MAC instance, where the 4 subframes may occurin two consecutive pairs of subframes. For instance, in one MAC instancethe set of subframes configured for HARQ feedback may be the set {0, 1,5, 6}. With this approach, for instance, subframe 0 may carry HARQfeedback for PDSCH transmissions having occurred in subframes {3, 4} ofthe previous frame, subframe 1 may carry HARQ feedback for PDSCHtransmissions having occurred in subframes {5, 6, 7} of the previousframe, subframe 5 may carry HARQ feedback for transmissions havingoccurred in subframes {8, 9} of the previous frame and subframe 0 of thecurrent frame, and subframe 6 may carry HARQ feedback for transmissionshaving occurred in subframes {1, 2} of the current frame. Otherarrangements are possible. In a second MAC instance, the set ofsubframes configured for HARQ feedback may be the set {2, 3, 7, 8} ifsubframe 0 of the second MAC instance starts between the beginning andthe end of subframe 0 of the first instance. This configurationcompletely avoids simultaneous transmission of HARQ feedback, even iftransmissions from both MAC instances are not synchronized at thesubframe level.

In a second example approach (for FDD), HARQ feedback may be restrictedto 3 out of 8 subframes for a MAC instance, where the 3 subframes mayoccur consecutively. With this type of approach, the subframes that maybe used for HARQ feedback (as well as other UCI) cannot be identifiedonly with a subframe number as these will change from one frame toanother. The pattern repeats over a period of multiple frames (e.g. 4 inthis case), and may be identified with an offset indicating the numberof subframes between the start of a period of 4 frames (e.g. thebeginning of a frame whose system frame number divides 4) and the firstsubframe of a group of 3 subframes that are configured to be used forHARQ feedback. Alternatively, the pattern may be identified with abitmap of 40 subframes. When this type of approach is employed, thefirst subframe of a group may for instance carry HARQ feedback for PDSCHtransmissions having occurred 9, 8 and 7 subframes earlier, the secondsubframe may carry HARQ feedback for PDSCH transmissions having occurred7, 6 and 5 subframes earlier (than the second subframe) and the thirdsubframe may carry HARQ feedback for PDSCH transmissions having occurred5 and 4 subframes earlier. This (and the previous approach) may requirean increase of the number of configured HARQ processes for PDSCH tosupport continuous transmissions. Similar to the previously describedapproach, the second MAC instance may be configured with a similarpattern that is designed to completely avoid simultaneous HARQ feedbacktransmission between MAC instances, even when transmissions are notsynchronized at subframe level. This can be achieved provided that thepattern of the second MAC instance is offset by between 3 and 4subframes with respect to the pattern of the first MAC instance (e.g. incase of synchronized system frame number and subframe 0 of the secondMAC instance starts between the start and the end of subframe 0 of thefirst MAC instance, the offset of the pattern of the second MAC instancemay correspond to the offset of the pattern of the first MAC instance,plus 3).

One potential benefit of the above arrangement is that all (synchronous)retransmissions of PUSCH may occur either in subframes that areconfigured to transmit HARQ A/N, or in subframes that are not configuredto transmit HARQ A/N. In case a higher priority is applied totransmissions carrying UCI (or HARQ A/N) over transmissions not carryingUCI, all PUSCH retransmissions for a HARQ process in the UL may haveeither a high priority or a low priority. In case high-priority data(e.g. signaling or voice) needs to be transmitted by the WTRU, thenetwork may elect to schedule PUSCH in those subframes configured forUCI transmission thus ensuring that any retransmission would sufferminimally from possible scaling.

Reporting functions for UL split bearers: A WTRU may be configured withdual connectivity, i.e. with one or more cells associated to a pluralityof eNBs (e.g. one MeNB and one SeNB). In such case, the WTRU mayimplement separate MAC entities, e.g. one for all cells associated toeach eNB in the WTRU's configuration. A WTRU configured with dualconnectivity may also be configured with one or more Data Radio Bearers(DRB) which DRB may be configured for uplink split. A WTRU may transmitdata associated to a DRB configured with UL split on either a cell of afirst MAC entity, of a second MAC entity, or both, either simultaneouslyor not.

In such case, the WTRU may be required to include a Buffer Status Report(BSR) in one or more of its uplink transmissions e.g. according tolegacy triggers possibly applied per MAC entity or duplicated acrossboth MAC entities in a case where the trigger is associated with a DRBconfigured with UL split.

Regarding the amount of data reported by the WTRU in such BSR for suchDRB, the following alternatives may be considered: The WTRU may reportthe same amount of data to both eNBs using legacy methods; or, the WTRUmay tailor the report using a configured ratio for the part applicableto PDCP.

However, the former alternative implies that schedulers may scheduleunnecessary uplink resources e.g. up to twice the required amount ofresources in the worst case, while for the latter case the uplinktransmission rate may be artificially limited as a consequence of thesemi-static ratio.

In a first approach, a new BSR trigger may be based on an impact fromanother scheduler.

This approach may, while not limited to such case, be used when the WTRUreport the same amount of data (or possibly, only for PDCP data) to botheNBs. To mitigate the possibility that both eNBs over allocate uplinkresources, the WTRU may implement additional BSR triggers.

This approach is based on a principle that even if the WTRU reports thesame (or similar) amount of data for a DRB configured with UL split,over-provisioning of uplink resources from the combined effect of bothindependent schedulers may be mitigated if the WTRU sends more BSRreports. However, to avoid unnecessary increase in the amount of BSR,rules may be defined such that BSR is included in an uplink transmissiononly if the status of the WTRU's buffer changes such that the likelihoodof receiving grants for too many uplink resources increases. Indeed,there may be no need to send BSR more often other than when the bufferis depleting quicker than the effect of a single scheduler.

For approaches discussed above, the BSR trigger may not lead to a SRtrigger.

In an approach, the WTRU MAC entity may trigger a BSR when it determinesthat the rate at which the buffer occupancy (and possibly, for the PDCPbuffer only) for a given DRB configured with UL split is being drainedby the other MAC entity exceeds a certain (possibly configurable)threshold. For example, a first WTRU MAC entity may determine that theamount of (e.g. PDCP) data transmitted using resources of a second WTRUMAC entity exceeds the amount of new data available for transmission bya value X during a given period since last time the WTRU MAC reportedBSR using uplink resources of the first MAC entity.

In another approach, the WTRU MAC entity may trigger a BSR when itdetermines that the amount of data in the WTRU's buffer (and possibly,for the PDCP buffer only) for a given DRB configured with UL split hasdropped by an amount that is a (possibly configurable) amount of datae.g. a factor X of the amount of data transmitted by the concerned MACentity. For example, a WTRU may trigger BSR when it determines that theamount of data available for transmission (e.g. either for the DRB i.e.both RLC and PDCP or for PDCP only) has dropped by an amount equivalentto a percentage larger than X % (where X is typically larger than 100)of the amount of corresponding data transmitted for the concerned DRBsince the last transmission of a BSR that included a value for such LCH(or LCG) using uplink resources of the first MAC entity.

PDCP buffer drops below a certain level as an effect of grants receivedin the other MAC entity: In another approach, the WTRU MAC entity maytrigger a BSR when it determines that the transmission rate of data inthe WTRU's buffer (and possibly, for the PDCP buffer only) for a givenDRB configured with UL split has changed by an amount that is a(possibly configurable) value X since the last transmission of a BSRthat included a value for such LCH (or LCG) using uplink resources ofthe first MAC entity.

Similarly, in another approach, this trigger could be based on anincrease in average transmission delay for PDCP SDUs, or reaching acertain amount of delay for the head-of-queue (i.e. the oldest PDCP SDUin the WTRU's buffer) or when the gap between the rate at which theWTRU's (e.g. PDCP only) buffer is drained by the other MAC entity andthe fill rate for such buffer increases beyond a certain value.Additional triggers may also be introduced for the opposite events.

In another approach, a BSR report may include RLC buffer occupancy only,and dynamic reporting may be used for PDCP.

This approach may, while not limited to such case, be used when the WTRUreports only the amount of RLC data in its buffer to each eNB inside theBSR. PDCP buffer occupancy may then rely on a separate mechanism and onadditional signaling from the WTRU which may be more dynamic. Forexample, such signaling may be included in some (or all) MAC PDUs for agiven MAC entity e.g. by re-using reserved bits inside the MAC subheader(e.g. “R” bits, or equivalent). Possibly, both MAC entities associatedto a DRB configured with UL split may implement such signaling and BSRreporting.

This approach may be based on the principle that a WTRU may alwaysreport the amount of data that it knows to be already associated to theconcerned MAC, e.g. RLC buffer occupancy and such as (possibly anestimation of the size of a) RLC STATUS PDU and/or RLCretransmission(s), and dynamically signal some approximate level for thePDCP occupancy for the concerned DRB. The dynamic signaling may provideinformation on the aggregated PDCP occupancy for one or more, or allDRBs configured for UL split. The BSR framework where PDCP occupancy isalso reported (but less frequently than the dynamic signalling) may beused in complement.

Such dynamic signaling may hereafter be referred to as Happy Bit(s).Possibly, happy bits are applicable only when at least one DRB isconfigured with UL split. The happy bits may signal information relatedto a single LCG and/or DRB or to the aggregation of a plurality of LCGsand/or DRBs configured with UL split, when such LCG only relate to DRBconfigured with UL split. The use of happy bits may also be aconfiguration aspect.

In another example that is a variant of the approaches below, the happybits are applicable to the DRB as determined by the LCID value in thesubheader in which the happy bits are included, if applicable.

In an approach, the WTRU MAC entity may report using BSR (or only for asubset thereof) only RLC buffer occupancy for a DRB configured with ULsplit. The WTRU may then include happy bit(s) according to e.g. at leastone of the following.

Single bit: when a single bit is used, the WTRU may signal whether theamount of PDCP data in the buffer is increasing or decreasing. Forexample, the WTRU may set the bit is the amount of data in the PDCPbuffer(s) has increased by an amount X since last transmission of a BSR(if used in complement) that reported a value for the concerned LCG(s)and/or DRB(s) or (if legacy BSR calculation is not applicable to ULsplit bearer) simply if that amount of data is larger than an (possiblyconfigurable) amount X. If a format is used whereby a single bit is usedper MAC PDU, such signaling may reflect the total amount of PDCP data inthe WTRU's buffer for all DRB configured with UL split. Alternatively,the WTRU may set the bit such that it indicates that the WTRU requestsuplink resources for the concerned LCG(s) and/or DRBs.

Two-bit field: when more than one bit is used, the WTRU may usecodepoints such as according to at least one of the following:

-   -   a. 00, 01, 10, 11 indicates relative buffer levels for the        concerned LCG(s) and/or DRB(s). Such values may be absolute        values. Alternatively, such values may be in relation to the        size of the transport block in which it is sent. Such values may        include “empty buffer” e.g. “00”, larger than or “infinite” e.g.        “11” with “01” and “10” as intermediate levels;    -   b. 00, 01, 10, 11 indicates approximate transmission rate for        the concerned LCG(s) and/or DRB(s) as calculated from        transmissions in the other MAC entity. Such values may be        absolute values. Alternatively, such values may be in relation        to the size of the transport block in which it is sent.        Alternatively, such values may be in relation to the        configuration of the (possibly aggregate) PBR for the concerned        DRB(s) and/or LCG(s).

The approach described above may be described in terms of LTE standards.For example, in LTE A MAC PDU subheader comprises the six header fieldsR/R/E/LCID/F/L but for the last subheader in the MAC PDU and for fixedsized MAC control elements. The last subheader in the MAC PDU andsubheaders for fixed sized MAC control elements consist solely of thefour header fields R/R/E/LCID. A MAC PDU subheader corresponding topadding comprises the four header fields R/R/E/LCID.

Further, a Reserved Bit is set to “0”, and a Buffer Size field indicatesthe total amount of data available across all logical channels of alogical channel group after all MAC PDUs for the TTI have been built.The amount of data is indicated in number of bytes, and includes alldata that is available for transmission in the RLC layer and in the PDCPlayer.

In these terms, if configured, the header fields R/R may become the HB(Happy Bit) field, and For a LCG associated to DRBs configured with ULsplit in the corresponding BSR format, data may include all data that isavailable for transmission in the RLC layer only.

The data available for transmission for RLC and for PDCP may remain asper legacy.

In another approach, the WTRU MAC entity may report using BSR (or onlyfor a subset thereof) only RLC buffer occupancy for a DRB configuredwith UL split. The WTRU may then include happy bit(s) such that the WTRUsignals average time-of-stay, head of queue delay, whether the PDCPbuffer levels tend to increase or decrease, or the difference betweenthe PDCP fill rate and what's drained by the MAC entity that signals thehappy bits. Similar signaling as described in the previous method may beused.

Prioritization of Data for Uplink Transmissions: A WTRU may beconfigured with dual connectivity, i.e. with one or more cellsassociated to a plurality of eNBs (e.g. one MeNB and one SeNB). In suchcase, the WTRU may implement separate MAC entities, e.g. one for allcells associated to each eNB in the WTRU's configuration. A WTRUconfigured with dual connectivity may additionally be configured withone or more Data Radio Bearers (DRB) which DRB may be configured foruplink split. A WTRU may transmit data associated to a DRB configuredwith UL split on either a cell of a first MAC entity, of a second MACentity or both either simultaneously or not.

In such case, the WTRU may receive a configuration for the DRB thatincludes an association with one Logical Channel (LCH) for each MACentity. In other words, a DRB may be associated to a plurality of LCHs,one for each MAC entity. For each LCH, the WTRU may additionally beconfigured with a priority value for the LCH, a PBR value and a BSDvalue; such value may be the same for all LCHs associated to the DRB(i.e. DRB-specific value) or may have separate values (i.e.LCH-specific).

Possible implementations for the LCP function in such case include:

-   -   a. Common bucket: the bucket Bj is shared across MAC entities        for the LCHs associated to the concerned DRB when performing        both LCP loops; and    -   b. Separate bucket: the bucket Bj is specific for each MAC        entity for the LCHs associated to the concerned DRB. The WTRU        performs the LCP loops separately for each MAC entity.

Each of these example implementations may have potential drawbacks. Forexample, the common bucket implementation may incur the risk ofintroducing starvation of RLC data (e.g. RLC STATUS PDU(s) and/or RLCretransmission) that is MAC-specific (i.e. RLC PDUs not associated to aPDCP SDU) e.g. when one scheduler (and consequently on MAC entity)consumes the entire bucket for an extended period of time thus denyingthe other MAC entity from serving the concerned DRB. The separate bucketimplementation may introduce jitter and/or may unexpectedly enable lowerpriority bearers to be served before higher priority bearers whenschedulers are poorly coordinated in the manner in which they assigntransmission resources.

Possibly, in combination with the methods described below, a LCHassociated with a bearer configured for UL split may only be assigned aLCG by itself or in combination with other LCH of the same type for thegiven MAC entity. Possibly, all such LCG have MAC-specific configurationfor the purpose of LCP.

In an approach, data for a split UL DRB subject to LCP procedure may bea function of the type of data in LCH. For bearers configured with ULsplit, assuming that the WTRU performs the LCP procedure for each MACentity using a common bucket Bj i.e. using a value for Bj that isDRB-specific as described above, in a first method the MAC entitydetermines what LCH to serve as part of the LCP procedure as a functionof the size of the bucket Bj but also as a function of the type of datain the RLC buffer. For example, the WTRU may include a LCH and serve itas part of the LCP procedure independently of the value of Bj at thetime it performs LCP if the concerned LCH has data of a specific typeeither pending (e.g. RLC STATUS PDU) or present in its buffer (e.g. RLCretransmission). For example, if the WTRU has a pending RLC STATUS PDUbut the associated Bj is zero or less, the WTRU may still include theLCH in the LCP procedure that results in allocation of data fortransmissions using resources of the concerned MAC entity. In such case,the WTRU may set the bucket Bj to the estimated (or actual) size of theRLC STATUS PDU. For example, if the WTRU has a RLC retransmission in itsRLC buffer but the associated Bj is less than the size of the RLCretransmission (including the case where it is zero or less), the WTRUmay still include the LCH in the LCP procedure that results inallocation of data for transmissions using resources of the concernedMAC entity. In such case, the WTRU may set the bucket Bj to theestimated (or actual) size of the RLC retransmission(s). Possibly, suchoperation is limited to the retransmission of one (e.g. nore-segmentation) or more PDU(s) (e.g. in case of re-segmentation)associated to the retransmission of a single RLC PDU. For example, in anexample case where both RLC STATUS PDUs and RLC retransmission(s) aresubject to such an approach, the WTRU may set the value of the Bj to thecombined value of their respective size.

The approach described above may be described in terms of LTE standardsfor logical channel prioritization. For example, in current LTEstandards resources are allocated to logical channels in a decreasingpriority order. According to the method described above, where Bj is avariable maintained by the WTRU indicating priority for each logicalchannel j, Bj for logical channels may be set as follows prior toallocating resources:

If Bj for a logical channel configured with UL split is less or equal to0, the UE shall

-   -   If there is a RLC STATUS PDU pending, the UE shall set Bj to the        size of the PDU.    -   If there is data in the RLC retransmission buffer, the UE shall        increment Bj to the size of the buffer.

Further, in current LTE standards a WTRU may take into account arelative priority of certain kinds of data. According to the methoddescribed above, a pending RLC STATUS PDU for any Logical Channel for aDRB configured with UL split may take priority over data in the RLCretransmission buffer for any Logical Channel for a DRB configured withUL split, but be lower in priority than a MAC control element for PHR orExtended PHR. Data in the RLC retransmission buffer for any LogicalChannel for a DRB configured with UL split may take priority over datafrom any Logical Channel, except data from UL-CCCH.

In another approach, a primary loop or loops may use MAC-specificparameters, and a secondary loop may use bearer-associated parameters.In an example, a WTRU may perform a LCP loop in a given MAC entity wherethe drain of the bucket associated to a LCH for a DRB configured with ULsplit may modify the value of the bucket for the LCH associated to theother MAC entity. In other words, exceeding the bucket size for a DRBconfigured with UL split in one MAC may be reflected in the bucket valueof the other MAC for the same DRB. More specifically, for bearersconfigured with UL split the WTRU may perform the LCP procedure suchthat the primary loop(s) (i.e. either only step 1 and step 2, or step 1up to step 3) for each MAC entity using parameters specific to each MACentity (LCH-specific parameters). It should be noted that here and inthe following discussion of LCP procedures, steps 1, 2, and 3 refer tothe steps of the LCP procedure described in the LTE specifications setforth above. Possibly, the priority is associated to the DRB itself orthe same value is used for all LCH(s) associated to the concerned DRB.

In a first example of this approach, a first MAC entity may perform step1 and step 2 using the PBR value and the BSD value configured for theLCH or, accordingly, the bucket size associated with the LCH; in thosesteps, the WTRU considers all LCHs associated with the concerned MACentity. The WTRU may then perform step 3 to allocate remaining resourcesconsidering all LCHs in decreasing priority order, which priority for aLCH associated with a DRB configured with UL split is either theDRB-specific value or the value associated to the LCH of the concernedMAC. In this first example, step 1 and 2 are the primary loop while step3 is the secondary loop. With step 3, if the aggregated sum of thebucket for all LCH(s) of the DRB with split UL is larger than zero, theWTRU may decrement the bucket associated to the MAC for which the LCH isbeing served by the amount of data served in step 3; if the resultingvalue becomes negative, the WTRU may transfer the negative part of thebucket value for that first LCH to the bucket value of a second LCHassociated to the concerned DRB and corresponding to the other MAC untileither the bucket value Bj of the second LCH reaches 0 (i.e. theabsolute value of the bucket size of the first LCH was larger than thepositive value of the first bucket size) or until the bucket value ofthe first LCH reaches 0 (i.e. otherwise).

In a second example of this approach, step 1, 2 and 3 that comprises twoloops are the primary loops and are performed using MAC-specific values,while the WTRU performs step 3 as one additional secondary loop as perthe first example for this method. In other words, in this secondexample one additional MAC-specific loop may be used compared to thefirst example.

The first example described above may be described in terms of LTEstandards for logical channel prioritization. For example, in currentLTE standards a WTRU allocates resources to logical channels byallocating resources to all the logical channels with Bj>0 in adecreasing priority order (where Bj is a variable maintained by the WTRUindicating priority for each logical channel j.). If the PBR of a radiobearer is set to “infinity,” the WTRU shall allocate resources for allthe data that is available for transmission on the radio bearer beforemeeting the PBR of the lower priority radio bearer(s). The WTRU thendecrements Bj by the total size of MAC SDUs served to logical channel j;and if any resources remain, all the logical channels are served in astrict decreasing priority order (regardless of the value of Bj) untileither the data for that logical channel or the UL grant is exhausted,whichever comes first. Logical channels configured with equal priorityshould be served equally.

In these terms, according to the first example described above, the WTRUmay decrement the value of Bj by the total size of the MAC SDU served tological channel j for a logical channel associated to a DRB configuredwith UL split; if the value Bj becomes negative, the WTRU shall transferas much of this negative amount to the bucket of the logical channelassociated to the concerned DRB in the other MAC entity such that eachbucket becomes of equal value (a negative value is possible).

The second example described above may also be described in terms of LTEstandards for logical channel prioritization discussed above.

In these terms, according to the second example described above, aftereither the data for the logical channel or the UL grant is exhausted, ifany resources remain, all the logical channels associated to a DRBconfigured with split UL are served in a strict decreasing priorityorder (regardless of the value of Bj) until either the data for thatlogical channel or the UL grant is exhausted, whichever comes first.Logical channels configured with equal priority should be servedequally. The WTRU shall decrement the value of Bj of the logical channelassociated to the concerned DRB in the other MAC entity such that eachbucket becomes of equal value (including a negative value).

Variants of the above examples are possible where the amount by whichthe bucket associated to each LCH of a DRB configured with UL split isvaried in different manners, including changing any negative value to azero value or resulting is unequal values using e.g. a ratio.

In another approach, data for a split UL DRB may be subject to LCPprocedure per bearer. For bearers configured with UL split, assumingthat the WTRU performs the LCP procedure for each MAC entity using acommon bucket Bj i.e. using a value for Bj that is DRB-specific asdescribed above, in this example approach the MAC entity determines whatLCH to serve as part of the LCP procedure using legacy logic; where theWTRU determines for a first MAC that a LCH is to be served, the LCP isperformed for the corresponding DRB for the first MAC entity but theWTRU also takes into account the amount of data that may be transmittedas a result of the LCP in the second MAC entity.

In another approach, a prioritization procedure may be run on aper-radio bearer basis. For example, a WTRU may perform LCP on aper-radio bearer basis using radio-bearer specific priorities. Usingthis approach, the WTRU may perform all the existing steps of the LCPprocedure on a radio bearer basis instead of on a LCH basis. In everystep, the WTRU may determine how much of the resources from each MAC areallocated to a radio bearer, possibly taking into consideration datafrom this RB that can only be transmitted to a certain MAC, such as RLCstatus PDU's or data in RLC buffers (e.g. segments). For each radiobearer, the WTRU may prioritize transmission of such MAC-specific data.

In the following discussion, example implementations of the aboveapproaches are described. For each example below, the WTRU is configuredwith a primary MAC entity (PMAC) and a secondary MAC entity (SMAC).

In an example of selective transmission, the WTRU may be scheduled by abase grant with a PUSCH transmission for a cell of the primary MACentity and with another base grant for a cell of a secondary MAC entity.The WTRU may determine that by performing both transmissionssimultaneously using their respective base grant, it would exceed itsmaximum transmission power; the WTRU then determines that aprioritization function should be applied. The WTRU may furtherdetermine that the PUSCH transmission of the primary MAC entity hashigher priority than the one of the secondary MAC entity, for example,because it contains control plane signaling. The WTRU may then determinethat it has a valid alternative grant suitable to replace the base grantof the transmission for the secondary MAC instance, and determines thatselective transmission may be used as the prioritization function forthe concerned transmissions. The WTRU may then perform the transmissionfor the primary MAC entity according to the base grant and the one forthe secondary MAC entity according to the alternative grant if thecorresponding transmissions are within the WTRU's maximum transmitpower; otherwise, the WTRU may perform additional (or alternate)prioritization.

In an example of explicit signaling, the WTRU may be configured suchthat transmissions associated to a SMAC have higher priority. In suchcase, the WTRU first allocate transmission power to the SMAC and anyremaining power to transmission(s) of the PMAC. Possibly, the WTRUdecodes uplink DCI format(s) associated to the PMAC such that aprioritization signal may be received.

The WTRU may be scheduled by a grant with a PUSCH transmission for acell of the primary MAC entity and with another grant for a cell of asecondary MAC entity. The WTRU may determine that by performing bothtransmissions simultaneously using their respective grant, it wouldexceed its maximum transmission power; the WTRU then determine that aprioritization function should be applied. The WTRU may furtherdetermine that the PUSCH transmission of the primary MAC entity hashigher priority than the one of the secondary MAC entity e.g. becausethe DCI received for the PMAC indicates that the transmission shall begiven higher priority. The WTRU may then perform the transmission forthe primary MAC entity according to the received grant and with higherpriority while possibly applying power scaling to other transmissions ifneeded. Such priority may remain for the duration of the concerned HARQprocess.

In another example, the WTRU may be configured such that transmissionsassociated to a SMAC have higher priority. In such case, the WTRU firstallocate transmission power to the SMAC and any remaining power totransmission(s) of the PMAC. Possibly, the WTRU decodes uplink DCIformat(s) associated to the PMAC such that a prioritization signal maybe received.

The WTRU may be scheduled by a downlink assignment with a PDSCHtransmission for a cell of the primary MAC entity and with another PDSCHtransmission for a cell of a secondary MAC entity. The WTRU maydetermine that in the subframe at which the WTRU is expected to transmitthe corresponding HARQ feedback for each transmission, it would exceedits maximum transmission power; the WTRU then determine that aprioritization function should be applied. The WTRU may furtherdetermine that the HARQ feedback associated to the PDSCH transmission ofthe primary MAC entity has higher priority than the one of the secondaryMAC entity e.g. because the DCI received for the PMAC indicates that thetransmission shall be given higher priority. The WTRU may then performthe transmission for the primary MAC entity accordingly (i.e. eitherusing PUSCH or PUCCH, depending of other scheduling informationapplicable for the concerned TTI) and with higher priority whilepossibly applying power scaling to other transmissions if needed. Suchpriority may remain for the duration of the concerned HARQ process e.g.until the HARQ feedback for the prioritized HARQ process is ACK.

In an example of simultaneous random access procedures toward differenteNBs, the WTRU has a first ongoing random access (RACH) procedure usinga first MAC entity. The WTRU then determines that a second RACHprocedure is triggered.

In another example, if the trigger for the second RACH procedure isassociated to the same MAC entity as the ongoing RACH procedure, theWTRU may perform using legacy behavior (i.e. the decision whether tocontinue with the ongoing procedure or to abort it and start a new oneis up to the WTRU implementation) while otherwise the WTRU performs bothprocedure concurrently. In the latter case, the WTRU always firstallocates power to a preamble transmission that is associated to thePCell of the PMAC entity; for preamble transmission associated to othercells of the PMAC, the WTRU determines how to allocate power as afunction of the priority between MAC entities: if the WTRU prioritizes aPRACH transmission for a PMAC instance before any other transmissionsassociated to the SMAC, the WTRU allocates power first to the PRACHtransmission associated to the PMAC and allocates remaining power toother transmissions; for a preamble transmission associated to the SMAC,the WTRU determines how to allocate power as a function of the prioritybetween MAC entities: if the WTRU prioritizes a PUSCH transmission for aPMAC instance before any other transmissions associated to the SMAC(e.g. in the offload case, which assumes that PMAC mainly handles higherpriority data) the WTRU allocates power first to transmissionsassociated to the PMAC and allocates remaining power to thetransmissions associated to the SMAC. If the WTRU determines that thepreamble associated to the SMAC cannot be transmitted at the expectedtransmission power, then, in one example, the WTRU scales thetransmission power for the transmission of the preamble but does notincrease the count of preamble transmissionPREAMBLE_TRANSMISSION_COUNTER (i.e. the WTRU may extend the totalduration of RACH procedure by up to a certain amount of transmissions atthe expense of longer UL RLF detection time). However, this may bebounded in total number of attempts and/or in time to avoid excessiveand unpredictable delay to the preamble transmission e.g. such that theWTRU may at most transmit up to an integer multiple of the maximumallowed/configured preamble transmission. One consequence of notincreasing the preamble count is that the power ramping is delayingaccordingly.

If no Random Access Response is received within the RA Response window,or if none of all received Random Access Responses contains a RandomAccess Preamble identifier corresponding to the transmitted RandomAccess Preamble, the Random Access Response reception is considered notsuccessful and the WTRU shall:

-   -   If power scaling was not applied to the transmitted Random        Access Preamble, increment PREAMBLE_TRANSMISSION_COUNTER by 1;    -   Else if power scaling was applied to the transmitted Random        Access Preamble, increment SCALED PREAMBLE_TRANSMISSION_COUNTER        by 1;    -   If PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1, or    -   If        PREAMBLE_TRANSMISSION_COUNTER+SCALED_PREAMBLE_TRANSMISSION_COUNTER=(2*preambleTransMax)+1:    -   if the Random Access Preamble is transmitted on the PCell:    -   indicate a Random Access problem to upper layers;    -   if the Random Access Preamble is transmitted on an SCell:    -   consider the Random Access procedure unsuccessfully completed.

Note: The WTRU always first allocate transmission power to a preambletransmitted on the PCell.

In one example that extends the previous example, the WTRU alwaysallocate power first to a preamble transmission initiated by PDCCH order(i.e. network-triggered RACH procedure);

If no Random Access Response is received within the RA Response window,or if none of all received Random Access Responses contains a RandomAccess Preamble identifier corresponding to the transmitted RandomAccess Preamble, the Random Access Response reception is considered notsuccessful and the WTRU shall:

-   -   If power scaling was not applied to the transmitted Random        Access Preamble, increment PREAMBLE_TRANSMISSION_COUNTER by 1;    -   Else if power scaling was applied to the transmitted Random        Access Preamble, increment SCALED_PREAMBLE_TRANSMISSION_COUNTER        by 1;    -   If PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1, or    -   If        PREAMBLE_TRANSMISSION_COUNTER+SCALED_PREAMBLE_TRANSMISSION_COUNTER=(2*preambleTransMax)+1:    -   if the Random Access Preamble is transmitted on the PCell:    -   indicate a Random Access problem to upper layers;    -   if the Random Access Preamble is transmitted on an SCell:    -   consider the Random Access procedure unsuccessfully completed.

Note: In case the random access procedure is initiated by a PDCCH orderfor the PCell, the WTRU always first allocate transmission power to thepreamble transmission.

In one example, the WTRU instead may transmit the preamble in asubsequent available PRACH occasion;

The Random Access Resource selection procedure shall be performed asdescribed in greater detail hereafter. The WTRU or Node-B may beconfigured to determine the next available subframe containing PRACHpermitted by the restrictions given by the prach-Configlndex, the PRACHMask Index and physical layer timing requirements (a WTRU may take intoaccount the possible occurrence of measurement gaps and availabletransmission power when determining the next available PRACH subframe);

In one example that extends the previous example, the WTRU transmits thepreamble in a subsequent available PRACH occasion for a preambletransmission initiated by PDCCH order (i.e. network-triggered RACHprocedure).

The Random Access Resource selection procedure may be performed asdescribed hereafter. The WTRU or Node-B determine the next availablesubframe containing PRACH permitted by the restrictions given by theprach-Configlndex, the PRACH Mask Index and physical layer timingrequirements (a WTRU may take into account available transmission powerin the case of a random access procedure that is not initiated for thePCell by a PDCCH order and the possible occurrence of measurement gapswhen determining the next available PRACH subframe).

In one approach, where the WTRU receives a RAR for an ongoing RACHprocedure, and the RAR includes a grant for an uplink transmission, theWTRU performs the following:

For a contention-based RACH (CBRA) procedure associated to the PMAC, theWTRU may prioritize any transmission associated to the HARQ process fortransmission of msg3. The WTRU may first allocate transmission power tothe corresponding (re)transmissions until the completion (successful ornot) of the concerned RACH procedure.

For a CBRA procedure associated to the SMAC, the WTRU may scale thetransmission power associated to the HARQ process for transmission ofmsg3, if necessary (i.e. if the WTRU prioritizes other transmissionse.g. transmissions for the PMAC). In this case, then the WTRU does notincrement the count of HARQ transmissions similarly as for the case ofthe preamble count described above.

For a contention-free RACH (CFRA) procedure associated to the PMAC, theWTRU prioritizes any transmission associated to the HARQ process thatuses the grant received in the RAR. The WTRU may first allocatetransmission power to the corresponding (re)transmissions until thecompletion (successful or not) of the concerned HARQ process. In oneexample, this may be done only for a RACH procedure associated to thePMAC. In another example, this may be done only for a RACH procedureassociated to the PCell of the PMAC.

For a CFRA procedure associated to the SMAC, the WTRU may prioritize anytransmission associated to the HARQ process that uses the grant receivedin the RAR for the SMAC such that such transmission have higher prioritythan any other transmission for the SMAC and also higher priority thanany PUSCH transmission for the PMAC which are not associated with anabsolute priority (e.g. a preamble transmission for PCell as per theabove, or a prioritized PUSCH transmission). The WTRU may allocatetransmission power to the corresponding (re)transmissions using suchpriority order until the completion (successful or not) of the concernedHARQ process. In one example, this may be done only for a RACH procedureassociated to the special cell of the SMAC.

In one approach, when the WTRU receives a RAR for an ongoing RACHprocedure, and the RAR includes a grant for an uplink transmission, theWTRU assigns the same priority level to the transmission associated withthe grant as it has previously assigned to the transmission of thepreamble.

In one approach, when the WTRU receives a RAR for an ongoingcontention-based RACH procedure and the RAR includes a grant for anuplink transmission, if the WTRU determines that a prioritizationfunction such as power scaling is applied to the transmission of msg3,the WTRU may exclude the time between the transmission and the nextretransmission of the msg3 from the contention resolution window.Possibly, the WTRU may also exclude the transmission from the count ofmsg3 (re)transmissions. Possibly, the latter may be limited up to amaximum delay for a successful msg3 transmission.

In one approach, if the WTRU cannot perform the transmission of apreamble in a given subframe due to some impairment (e.g. total WTRUtransmission power exceeds the allowed maximum) the WTRU prioritizes thetransmission of the preamble only for the RACH procedure associated tothe PMAC entity by first allocating transmit power to this transmission.Similarly, the same approaches may be applied to the transmission ofmsg3.

Semi-static priority and dynamic signaling to override configuration: Inone approach, the WTRU may be configured with a semi-static prioritybetween MAC instances and the WTRU may receive control information thatoverrides such configuration for a scheduled transmission which controlinformation may be received together with the corresponding schedulinginformation. More specifically, the WTRU may be configured with a firstMAC instance and with a second MAC instance. The WTRU may be configuredsuch that power is normally first allocated to transmissions associatedto the second MAC instance. The WTRU then may apply legacy power scalingacross transmissions associated to a given MAC instance when the WTRUdetermines that insufficient power is available for transmissions in agiven TTI. The WTRU may additionally be configured such that it canreceive physical layer control signaling on a cell associated to thefirst MAC instance. The control signaling may be received in a downlinkcontrol information (DCI) on the scheduling channel such as PDCCH andmay include control information that dynamically modifies the configuredpriority of the power allocation such that power is first allocated tothe first MAC instance. Such control signaling may be applicable to adownlink assignment and/or to an uplink grant. The WTRU may prioritizetransmissions associated to the first MAC instance when it receives suchcontrol signaling with a downlink assignment such that at least thetransmission of HARQ feedback is prioritized, or when it receives suchcontrol signaling with an uplink grant such that at least thetransmission of data on PUSCH is prioritized.

PHR triggered by reception of dynamic signaling and power scaling event:In one approach, the WTRU may trigger a PHR where the absolute priorityapplicable between MAC instances was last set by reception of dynamiccontrol signaling and where the WTRU determines that power scaling isapplied to at least one transmission associated to a MAC instance forthe first time since the reception of such control signalling. The WTRUmay trigger the PHR in the TTI for which power scaling is applicable or,the WTRU may trigger the PHR such that a PHR may be included in atransmission for the concerned TTI. The WTRU may trigger PHR at leastfor a first MAC instance when it determines that power scaling isapplied to at least one transmission of a second MAC instance and whenthe absolute priority between MAC instances was modified by dynamiccontrol signaling such that power was first allocated to transmissionsassociated to the first MAC instance.

Synchronous and Asynchronous Uplink Transmissions across CGs: The WTRUmay apply a first prioritization function (e.g. a power allocationmethod and/or a scaling) when it determines that uplink operationbetween configured CG's is synchronous and a second prioritizationfunction where it determines that uplink operation between configuredCG's is asynchronous.

The WTRU may determine to allocate power using proactive scaling (i.e.with look ahead) for synch case, and with guaranteed power otherwise.For example, the WTRU may determine that it should perform powerallocation according to a first method if it determines that the uplinkoperation is synchronous and according to a second method otherwise. Forexample, the first method may be based on a determination of the powerallocated to each CG by considering required power for each CG, while asecond method may be based on a determination of the power allocated toeach CG based on the required power for the CG for which transmissionsstart earliest in time and based on a guaranteed amount of power for theother CG.

The WTRU may determine to perform power scaling using scaling over bothcell groups for synch case, and using allocation by cell group andscaling by cell group otherwise. For example, the WTRU may determinethat it should perform power scaling according to a first method when itdetermines that the uplink operation is synchronous and according to asecond method otherwise. For example, the first method may be based onscaling transmissions by considering all transmissions across both CGsaccording to priority between such transmissions (e.g. by type), while asecond method may be based on scaling power per CG e.g. by firstallocating power per CG and then performing scaling across transmissionsof a given CG only.

Example methods for a WTRU to determine whether an uplink operation issynchronous or asynchronous are described further herein.

In one example, the WTRU may determine whether an uplink operation issynchronous or asynchronous based on an L3 indication from MeNB. TheWTRU may receive an indication from the network such that it maydetermine whether or not the uplink operation is synchronous e.g. by L3RRC signaling during a RRC Connection Reconfiguration procedure. Suchreconfiguration procedure may include a reconfiguration that adds ormodifies at least one aspect of the WTRU's configuration for a SCG. Forexample, the network may indicate whether or not an uplink operation issynchronized using RRC signaling that adds at least the special cell(i.e. that initially configures the SCG for the WTRU) and/or thatmodifies the configuration of such special cell of the SCG (e.g. suchthat the cell is changed.) This may, for example, be applicable in acase where the uplink operation is determined by the network and as afunction of the DL timing difference between the PCell of the MCG andthe special cell of the SCG.

In one method, the WTRU may determine whether an uplink operation issynchronous or asynchronous based at least in part on WTRU autonomousbehavior. In one method, the WTRU may determine the type of uplinkoperation autonomously and/or the WTRU may monitor the relative timingsynchronization between cells of different CGs such as to detectpossible synchronization error. For example, the WTRU may receiveexplicit signaling from the network that indicates synchronous uplinkoperation between CGs; where configured for dual connectivity, the WTRUmay then monitor the synchronization between cells of the CGs e.g.according to methods described herein and, in case it detects asynchronization problem, perform error handling as described below.

In an example, the WTRU may receive L3 RRC signaling that indicates thatthe uplink operation is synchronous between cells of different CGs. TheWTRU may then use a single behavior for allocation of power betweendifferent CGs. Possibly, the WTRU may monitor DL timing of the PCell ofthe MCG and that of the special cell of the SCG such that it may detectif it exceeds a specific threshold and/or detect that synchronization isabove such threshold when it performs uplink transmissions such that itmay not comply for at least one uplink transmissions; in this case, theWTRU may perform error handling as described below.

In another example, the WTRU may receive L3 RRC signaling that indicatesthat the uplink operation is asynchronous between cells of differentCGs. The WTRU may then use a single behavior for allocation of powerbetween different CGs. In such case, the WTRU may not be required tomonitor for synchronization problems between cells of different CGs.

In a further example, the WTRU may receive L3 RRC signaling thatindicates that the uplink operation is asynchronous between cells ofdifferent CGs. The WTRU may then monitor for the timing differencebetween cells of different CGs e.g. according to other methods describedherein. The WTRU may perform power allocation according to a firstmethod if it determines that the uplink operation is synchronous andaccording to a second method otherwise.

Further WTRU autonomous methods related to how UE monitors, detectssynchronization between CGs are discussed herein.

In one approach, whether the WTRU operates synchronously orunsynchronously (or asynchronously) with respect to uplink transmissionsbetween its configured cell groups (CG) may be defined based on therelative time difference between the start of the CG's respective ULsubframe.

For example, the WTRU may consider that the uplink operation betweenconfigured CGs is synchronous if the time difference between the startof the CG's respective UL subframe is less than or equal to a specificthreshold. Such threshold may be specified as a fixed value, may bebounded by the guard time between two consecutive subframes in thesystem, or it may be a configuration aspect. Optionally, such thresholdmay include a hysteresis period such that if the WTRU may transitbetween one mode (e.g. synchronous) and the other mode (e.g.asynchronous) the WTRU does not perform unnecessary transitions whenoperating close to such threshold. For example, the WTRU may transmit tothe unsynchronous mode of uplink operation upon reaching such threshold,but may remain in this mode only until the relative time differencereverts to less than the threshold minus an additional period of time X(i.e. the WTRU would move quickly to the unsynchronized mode but remainin such mode until it goes back within a fair margin of the threshold).

Evaluation of Time difference between CGs: More generally, if the WTRUis configured with multiple TAGs for a given CG, such time differencemay be determined based on at least one of the following:

PCell to SpSCell: The start of the uplink subframe associated to the TAGthat contains the CG's special cell. For example, this may be the PCellfor the primary CG (MCG), and the Special SCell (e.g. the SCell that isconfigured with PUCCH resources and/or for which RLM is performed) forthe secondary CG (SCG). For example, in this case the relative timedifference would be the difference between the start of the uplinksubframe of the PTAG of the MCG and the start of the uplink subframe ofthe PTAG of the SCG. In this case, the term “applicable cells” when usedhereafter refers to those cells for this method.

Largest absolute value between start of any two transmissions: The startof the uplink subframe associated to the TAG of the MCG and that of theTAG of the SCG for which the relative time difference is the largest inabsolute value. In this case, the term “applicable cells” when usedhereafter refers to any cell of the concerned TAGs for this method.

Largest absolute value between start of any two uplink subframes: Thestart of the uplink subframe associated to the TAG of the MCG for whichthe WTRU performs at least one transmission in this subframe, and thatof the TAG of the SCG for which the WTRU performs at least onetransmission in this subframe, in between which the relative timedifference is the largest in absolute value. In this case, the term“applicable cells” when used hereafter refers to any applicable cell(s)(e.g. for which the WTRU performs at least one transmission) of theconcerned TAGs for this method.

Largest absolute value between start of a transmission in PCell and anytransmission in a SCG: The start of the uplink subframe associated tothe PTAG for the MCG, and the start of the uplink subframe associated tothe TAG of the SCG for which the resulting relative time difference isthe largest in absolute value. In this case, the term “applicable cells”when used hereafter refers to the PCell and to any cell of the concernedTAG of the SCG for this method.

If the WTRU determines such time difference only when it performs uplinktransmissions in cells that are applicable for the concerned method asdescribed above, or only when it performs at least one uplinktransmission in at least one cell of each CG, then the WTRU may considerthe start of an applicable transmission as the start of the uplinksubframe (possibly with the exception of a transmission signal that doesnot span all symbols of a subframe e.g. SRS).

Determination of the uplink operational mode: In one approach, the WTRUmay determine the applicable operational mode according to at least oneof the following:

Based on L3 signalling/configuration: The WTRU may determine theapplicable uplink operational mode from an indication received by L3signalling. In such case, the type of uplink operational mode may be asemi-static component of the WTRU's configuration. For example, the WTRUmay receive control signaling that indicates the uplink operational modeas part of the configuration for dual connectivity. For example, theWTRU may receive the type of uplink operational mode as part of theconfiguration for dual connectivity that first adds a SCG. This mayinclude whether the WTRU shall assume synchronous operation only,asynchronous operation only or possibly, this may include an indicationthat the WTRU shall autonomously determine the uplink mode of operation,for example according to any of the methods described herein. Possibly,the WTRU may receive as part of the configuration an indication of theapplicable power allocation function. Possibly, the WTRU may receive aconfiguration of a power allocation function for the concernedapplicable operational mode.

Relative timing difference between CGs calculated based on downlinktiming reference for the applicable cell of the CG: The WTRU mayestimate the amount of time difference between corresponding downlinksubframe of the applicable cell of each CG. The WTRU may compare suchtime difference with a threshold, from which comparison it may determinewhether the uplink operational mode is synchronous or asynchronous. Suchthreshold may be a configuration aspect of the WTRU. The WTRU configuredwith dual connectivity may determine the applicable uplink operationalmode by evaluating the relative timing difference between applicablecells of different CGs and comparing it to such threshold.

Relative timing difference between CGs calculated based on uplinksubframe alignment for the applicable cell of the CG, using received TAC(or Nta_ref): The WTRU configured with dual connectivity may determinethe applicable uplink operational mode by evaluating the relative timingdifference between applicable cell of different CGs and comparing it toa threshold.

The WTRU may estimate the amount of time difference betweencorresponding uplink subframe of the applicable cell of each CG. Suchestimation may be performed using the respective amount of timingcompensation applied to each cell as a result form the last received TACfor each applicable cell.

The WTRU may estimate the time difference when a stored UL timingreference changes e.g. as a result of NW signaling: In such case, theWTRU may perform such estimation at least before it first performs oneor more transmissions in each CG which occur simultaneously at orfollowing the subframe in which the TAC is first applied. Possibly, onlywhen such transmissions would require the use of a power allocationfunction for a power-limited situation. For example, the WTRU mayperform such estimation when it receive a TAC, when it first apply thereceive value in the TAC, when it first receives at least one grant foreach CG that leads to simultaneous transmission after the last receptionof at least one TAC, or when it first determines that power is to beallocated such that it exceeds either the total available power for a CG(if less than the maximum available WTRU transmit power) and/or themaximum available WTRU transmit power for such simultaneoustransmissions.

The WTRU may compare such time difference with a threshold, from whichcomparison it may determine whether the uplink operational mode issynchronous or asynchronous. Such threshold may be a configurationaspect of the WTRU.

Relative timing difference between CGs calculated based on uplinksubframe alignment for the applicable cell of the CG, using Nta (orincluding the WTRU-autonomous compensation): The WTRU configured withdual connectivity may determine the applicable uplink operational modeby evaluating the relative timing difference between applicable cell ofdifferent CGs and comparing it to a threshold.

The WTRU may estimate the amount of time difference betweencorresponding uplink subframe of the applicable cell of each CG. Suchestimation may be performed using the respective amount of timingcompensation applied to each cell as a result of the WTRU's autonomouscompensation mechanism e.g. from changes in DL timing.

The WTRU may estimate the time difference when UL timing compensationchanges without NW involvement: In such case, the WTRU may perform suchestimation in any subframe for which it determines whether or not itshould autonomously apply a compensation (for example, by tracking DLtiming). In some implementations, this may be done only in a subframewith PSS/SSS. Alternatively, the WTRU may perform such estimation atleast before it first performs one or more transmissions in each CGwhich occur simultaneously with, or following, the subframe in whichcompensation is autonomously applied. In some implementations this maybe done only when such transmissions would require the use of a powerallocation function for a power-limited situation. For example, the WTRUmay perform such estimation where it first determines a change in DLtiming for at least one applicable cell, where it first applies suchcompensation to the uplink timing, where it first receives at least onegrant for each CG that leads to simultaneous transmission after it lastautonomously adjusted the compensation, or where it first determinesthat power is to be allocated such that it exceeds either the totalavailable power for a CG (if less than the maximum available WTRUtransmit power) and/or the maximum available WTRU transmit power forsuch simultaneous transmissions.

The WTRU may compare such time difference with a threshold, from whichcomparison it may determine whether the uplink operational mode issynchronous or asynchronous. Such threshold may be a configurationaspect of the WTRU.

The WTRU estimates the time difference for compensation of DL timingchanges: For any of the WTRU-autonomous methods described above that arebased on estimation of DL timing, the WTRU may perform such comparisondynamically e.g. according to at least one of the following:

Continuously, for DL: in every subframe (e.g. continuously), or in everyDL subframe (e.g. continuously for DL subframes in TDD), or in every DLsubframe in which the WTRU decodes PDCCH for at least one applicablecell in each CG (e.g. when the WTRU is in DRX active time).

When a WTRU may autonomously determine that it should apply acompensation for DL timing changes if such is detected: in a subframefor which the WTRU estimates DL timing for at least one applicable cellof a CG (e.g. based on using a cell used as DL timing reference for theconcerned TAG and/or CG).

Only when PSS/SSS is available: in a subframe in which the WTRU decodesPSS/SSS.

Only after it adjusted UL timing, and first when it needs to apply apower allocation function since then: following a subframe in which itdetermines that a compensation should be applied, when it firstdetermines that it has uplink resources available to perform one or moretransmissions in each CG (or that it needs to allocate power for such)which occur simultaneously for both CGs.

The WTRU estimates the time difference in relation to maintenance of ULtiming: In addition, for any of the WTRU-autonomous methods describedabove that are based on maintenance of UL timing, the WTRU may performsuch comparison dynamically e.g. according to at least one of thefollowing:

-   -   a. WTRU receives/applies TAC: in a subframe for which it        receives (or apply) a received TAC (or updates Nta_ref).    -   b. WTRU autonomously updates Nta: in a subframe for which the        WTRU determines that it should autonomously add a compensation        to the uplink timing alignment (Nta) e.g. based on change in        estimated DL timing, or when it first apply it.    -   c. Combinations of a. and b. are also possible.

The WTRU may use different power allocation behavior as a function ofdetermined operational mode. In one approach, the WTRU may use a firstpower allocation method if it determines that it operates in thesynchronized mode, while it may use a second power allocation functionif it determines that it operates in the asynchronous mode. For example,the first power allocation function may implement power sharing suchthat power may be dynamically allocated between transmissions associatedto different CGs while the second power allocation methods may implementa semi-static splitting function of the total available WTRUtransmission power between transmissions associated to different CGs.

The WTRU may support, as a WTRU capability, whether or not it is capableof dynamic power allocation independently of the operational mode. Inone approach, the WTRU may report as part of the WTRU capabilityexchange whether or not a single method may be applied to bothsynchronous and asynchronous uplink operation when configured with dualconnectivity. For example, the WTRU may report that it may be capable ofdynamic power sharing for the power allocation function for both modes.Such capability would typically imply a specific level of implementationcomplexity, which may for example require additional processing such asproactive power allocation. For example, the WTRU may report that it maybe capable of dynamic power sharing for the power allocation functiononly in one mode. For example, such mode may be the synchronous mode.Such capability would typically require less implementation complexity.When the WTRU receives a configuration for dual connectivity, suchreported capability may implicitly determine that a specific powerallocation behavior shall be used for the synchronous and/or for theasynchronous mode. For example, such power allocation behavior may be adynamic power sharing function for the synchronous case, while it may bea semi-static splitting function for the unsynchronous case. Possibly,the WTRU may include information related to the type of power allocationsupported for dual connectivity. The WTRU may report as part of theWTRU's capability a value that represent the maximum processing delaythat may be added for the purpose of power allocation. Such value may besignaled as a maximum time difference that may be applicable betweenuplink subframes of different CGs.

New PHR trigger: The WTRU may trigger a PHR when it determines that itshould perform a switch of the uplink operational mode. Possibly, theWTRU trigger such PHR when it determines that it should perform at leastone uplink transmission in each CG simultaneously for the first timesince it last performed a switch in uplink operational mode. Possibly,only if such transmission requires the application of a power allocationfunction that implement some form of prioritization (including scaling)and/or sharing of the total WTRU available power.

WTRU assistance for determination of the timing difference between cellsis discussed further herein. The WTRU may be configured to measure DLtiming for one or more cells. For example, such cells may correspond toone or more cells of the measurements configuration. The WTRU mayadditionally be configured to report the DL timing difference betweensuch cells and the PCell of the WTRU. For example, such report mayinclude whether or not the difference in timing is above or below athreshold. Alternatively, such timing difference may be an absolutevalue as a function of the granularity of the reporting. For example,such reports may be transmitted together with measurements reports, e.g.when such measurement reporting is triggered according to existingmeasurements triggers.

Handling of error cases; Determination of error case: The WTRU maydetermine that there is a problem with its uplink operation with dualconnectivity (e.g. a radio link problem with the SCG) when it determinesthat the time difference between CGs exceeds a threshold. Possibly, suchthreshold relates to a capability of the WTRU. Possibly, such thresholdmay be the same threshold as described above and used for thedetermination of the uplink mode of operation. For example, the WTRU mayonly have the capability of operating with dual connectivity for thesynchronized mode of uplink operation and make such determination e.g.using any of the methods described herein.

Action upon occurrence of an error case: When the WTRU determines suchproblem, the WTRU may perform at least one of the procedures describedin greater detail herafter.

-   -   a. The WTRU may consider that it no longer has valid UL timing        alignment (e.g. TAT is expired).        -   i. Possibly, only for one (or all) TAG(s) of the SCG.    -   b. The WTRU may report the error situation to the network, e.g.        to the MeNB using L3 signalling.        -   i. Such L3 signalling may include a RRC procedure.        -   ii. Such RRC procedure may be the procedure used to report            radio link failure (RLF) of the SCG (S-RLF) to the MeNB.        -   iii. Such report may include the cause e.g. as being            “incorrect synchronization”.        -   iv. The WTRU may stop the connection to the SCG, and may not            resume it autonomously.    -   c. The WTRU may invalidate the SCG configuration.    -   d. The WTRU may trigger a PHR for the MCG.    -   e. The WTRU may initiate the RRC Connection Re-establishment.

Handling of SRS transmissions is described further herein.

In a legacy behavior, the SRS may typically be transmitted in the lastsymbol of a subframe.

In another legacy behavior, a WTRU configured with multiple TAGs maytypically drop the SRS transmission if it overlaps with the PUCCH/PUSCHtransmission for a different serving cell (same or different TAG) in thesame subframe or in the next subframe, if the WTRU's total transmitpower would otherwise exceed the maximum available transmission power(e.g. Pcmax) on any overlapped portion of the symbol.

In a further legacy behavior, a WTRU configured with multiple TAGs andmore than 2 serving cells may typically drop the SRS transmission if itoverlaps with the SRS transmission of a different serving cell in thesame subframe and if it overlaps with the PUCCH/PUSCH transmission foranother serving cell in the same subframe or in the next subframe, ifthe WTRU's total transmit power would otherwise exceed the maximumavailable transmission power (e.g. Pcmax) on any overlapped portion ofthe symbol. When compared with the previous rule, it is akin toselection of what SRS to drop in such case (as the other SRS may notoverlap with the PUCCH/PUSCH transmission).

In another legacy behavior, a WTRU configured with multiple TAGs maytypically drop the SRS transmission if it overlaps with thenetwork-controlled PRACH transmission in a SCell of a different TAG ifthe WTRU would otherwise exceed the total WTRU available power (e.g.Pcmax) for any overlapping portion of the symbol.

Legacy dropping rules for SRS can be applied when more than two TAGs areconfigured and/or when multiple CGs are configured i.e. dualconnectivity. In one method, the legacy rules for dropping SRS may beapplicable for a WTRU configured with dual connectivity, including thecase where SRS transmission overlaps with PUCCH/PUSCH for either thePCell of the MCG or the special cell of a SCG.

Legacy scaling rules for SRS may be only applicable within one CG, andunless legacy dropping rules considered for all transmissions of theWTRU do not lead to dropping a SRS. In one method, a WTRU configuredwith dual connectivity may scale the power allocated to the transmissionof a SRS signal according to legacy rules if and only if all concernedSRS transmissions are performed on cells of the same CG. Possibly, thismay be done also when the WTRU's total transmit power for the concernedCG would otherwise exceed the maximum available transmission power forthe CG (e.g. Pcmax,enb) on any overlapped portion of the symbol. In oneexample, if the CG is configured with at most one serving cell withuplink resources (e.g. the PCell of the MCG or the special cell of theSCG), the maximum WTRU transmit power of the concerned CG (e.g.Pcmax,enb) may be equivalent to the total WTRU available power for theconcerned cell (e.g. Pcmax,c).

The WTRU may determine that it should transmit one or more SRS signalsassociated to a specific CG. The WTRU may make such determinationaccording to any of the methods described below, for example to handlecases where SRS may overlap in time between CGs and/or where SRSoverlaps with other transmissions of the same or different CGs, or thelike.

Overlapping SRS across CGs are discussed further herein.

In a case where Pcmax is exceeded, SRS may be dropped if two SRStransmissions from different CGs overlap and Pcmax is exceeded. In onemethod, the WTRU configured with dual connectivity may drop thetransmission of a SRS if the transmission of the SRS in a symbol for aserving cell of a first CG overlaps with a SRS transmission in a symbolfor a serving cell in another CG and if the total transmit power of theWTRU in the overlapped portion would exceed the total WTRU availablepower (e.g. Pcmax).

In a case where Pmax per CG is exceeded, for one CG, SRS may be droppedif two SRS transmissions from different CGs overlap and Pmax,eNBexceeded. In one method, the WTRU configured with dual connectivity maydrop the transmission of a SRS if the transmission of the SRS in asymbol for a serving cell of a first CG overlaps with a SRS transmissionin a symbol for a serving cell in another CG and if the total transmitpower associated to the concerned CG in the overlapped portion wouldexceed the total WTRU available power for the concerned CG (e.g.Pcmax,enb). In one example, if the CG is configured with at most oneserving cell with uplink resources (e.g. the PCell of the MCG or thespecial cell of the SCG), the maximum WTRU transmit power of theconcerned CG (e.g. Pcmax,enb) may be equivalent to the total WTRUavailable power for the concerned cell (e.g. Pcmax,c).

Overlapping between SRS and PRACH across CGs is discussed furtherherein. There is no handling in legacy behavior for the case where thetransmission of SRS would overlap with the transmission of aWTRU-autonomous preamble (e.g. RA-SR). However this case is now possiblewith dual connectivity.

WTRU-autonomous PRACH in MCG and SRS in SCG is discussed further herein.In one method, a WTRU configured with dual connectivity may drop a SRStransmission for a serving cell of a first CG if it overlaps with atransmission on PRACH for a serving cell of another CG if the WTRUtransmit power would otherwise exceed a maximum available power. Thismay be done only if the WTRU's total transmit power exceeds its maximumavailable power (e.g. Pcmax) for the overlapped portion. This may alsobe done if the PRACH transmission cannot be allocated up to its requiredpower using the corresponding CG's guaranteed power allocation. Further,this may be done only if the preamble transmission is for acontention-free random access, or only if the serving cell of the secondCG is the special cell of a SCG. This may also be done if the WTRU'stransmit power for a given CG exceeds a maximum available power for thatCG (e.g. Pcmax,enb).

SRS transmission power within the framework of guaranteed power andpower sharing is discussed further herein. Once the WTRU has determinedthat it should perform SRS transmission(s), it may allocate poweraccording to one or more of the following methods:

SRS transmission power capped by the guaranteed power of the CG: Forexample, the WTRU may allocate transmission power to SRS such that theamount of power allocated to the SRS transmission(s) does not exceed theguaranteed power for the CG. In other words, the sounding procedure maytake into account the configuration of the power allocation function andthe split allocation between eNBs for the guaranteed part of the totalWTRU power.

SRSx for CG_(x) may be from 0 up to max [P_(XeNB)]: For example, theWTRU may allocate power (e.g. SRSx) to SRS transmission(s) for a firstCG (e.g. CG_(X)) to at most up to the total WTRU available power (e.g.P_(CMAX)) less the guaranteed power of the other CG (e.g. P_(XeNB)).

In particular for PCM2: For example, the WTRU may perform suchallocation of power for a specific power control method, e.g. such asfor a power allocation method where any remaining power may be allocatedto transmission(s) of the group of cells (or CG, or MAC instance) forwhich the transmissions start earliest in time (e.g. PCM2).

SRS_(X) for CG_(x) may be from 0 up to max [P_(XeNB),P_(CMAX)-P_(YeNB)]:

In particular for PCM1: For example, the WTRU may allocate any unusedpower in the other CG if the WTRU can determine the exact powerrequirements of any possible overlapping transmissions at least ahead ofthe transmission of the SRS (e.g. the WTRU is capable of look-ahead). Inother words, the sounding procedure may additionally take into accountthe part of the total WTRU power that is not used by the otherscheduler, when necessary, as a dynamic component of the SRS powerallocation.

For example, for PCM1 (WTRU is capable of look ahead), SRS may use up tothe maximum available power (e.g. P_(CMAX)) less the power allocated tothe other CG (e.g. PcG_(y)) e.g. P_(CMAX)-P_(CGy).

For example, for PCM2 (WTRU does not perform look ahead), SRS may use upto the maximum available power (e.g. P_(CMAX)) less the guaranteed powerof the other CG (e.g. P_(YeNB)) e.g. P_(CMAX)-P_(YeNB).

For example, the WTRU may perform the following:

-   -   The WTRU may first determine the desired amount of power for the        SRS transmission(s) of the CG, using applicable power control        formulas for SRS e.g. as per legacy methods;    -   The WTRU may determine that the maximum amount of power than can        be allocated to the SRS transmission(s) for the CG is the        maximum available power (e.g. PCMAX) less the guaranteed power        of the other CG (e.g. P_(YeNB)); in case the other CG has        on-going transmissions higher than its guaranteed power at the        beginning of the subframe, the maximum power of SRS may be        limited by the maximum available power less the power of the        on-going transmission. In case other transmissions (PUCCH/PUSCH)        continue in the symbol containing SRS for the same CG, the        maximum power of SRS may be further reduced by the power of        these continuing transmissions;    -   If the WTRU determines that the desired power is more than the        maximum amount of power available for SRS, the WTRU may either        drop or scale the SRS transmission(s). Possibly, the scaling may        be performed according to legacy methods for SRS scaling.

The WTRU may possibly perform the above power allocation method for SRStransmission(s) if the maximum power level allocated to PUSCH/PUCCHtransmission(s) associated to the same CG and for the same subframe doesnot exceed the power level of the SRS.

The WTRU may possibly perform the above power allocation method for SRStransmission(s) if the WTRU does not perform any PUSCH/PUCCHtransmission associated to the same CG and for the same subframe.

The WTRU may possibly perform such power allocation function dependingon the type of trigger for SRS; for example, the WTRU may perform theabove power allocation function for periodic SRS transmissions.

SRS transmission power capped by the PUSCH/PUCCH power of the same CG isfurther discussed herein. In some implementations, SRS transmissionpower may always be capped by the amount of power allocated toPUSCH/PUCCH power. SRS_(X) for CG_(X) may be from 0 up to [PC_(Gx)),(PUSCH/PUCCH)]

For example, the WTRU may determine that it should transmit (one ormore) SRS signal associated to a specific CG. The WTRU may allocatetransmission power to SRS such that the amount of power allocated to theSRS transmission(s) does not exceed an amount of power as calculated forPUCCH/PUSCH transmissions of the same CG in the same subframe, if any.Such amount of power may include at least one of the following:

-   -   a. The power allocated to the PUSCH/PUCCH transmission(s) for        that CG (e.g. P_(CGx) (PUSCH/PUCCH)). This may be a simple        alternative complexity-wise but may yield a slightly less        accurate power level for SRS.    -   b. The upper bound (e.g. P_(CMAX) _(_) _(high)) of the power        range determined in the calculation of the maximum power that        may be allocated to the PUSCH/PUCCH transmission(s) for that CG        before applying a power reduction due to e.g. MPR, A-MPR. This        may be useful to remove the impact of the power reduction        applied to PUSCH/PUCCH transmissions (which power reduction is        specific to the type of transmission and to the type of        modulation e.g. the applied reduction is typically less for QPSK        than for higher modulation order such as 16QAM) and may be        slightly more complex at least when the modulation order differs        for PUSCH/PUCCH transmissions and for SRS transmissions.    -   c. A power level in a range that may be different than the other        subframe symbols and specifically determined for the SRS(s)        symbol based on its specific applicable MPR or A-MPR. This may        be the most accurate approach in all situations.

In one example, the power for SRS is always limited by the amount ofpower allocated to the PUSCH/PUCCH when there is such a transmission inthe same subframe and for the same CG. In one example, the power for SRSmay be limited by the maximum amount of power that can be allocated toPUSCH/PUCCH transmission(s) before applying a power reduction (such asMPR, A-MPR) when there is such transmission(s) in the same subframe andfor the same CG. For example, the WTRU may allocate power to the SRStransmission up to the upper bound of the P_(CMAX) range (e.g. P_(CMAX)_(_) _(high) of the PUSCH/PUCCH) for the CG when calculating the valueof P_(CMAX) for PUSCH/PUCCH transmission(s) of the CG.

In other words, the sounding procedure may take into account the powerallocated to the CG in a given subframe, as a dynamic component of thepower allocation function for SRS.

The WTRU may perform such allocation of power for a specific powercontrol method, for example such as for a power allocation method whereany remaining power may be allocated to the CG with transmission(s) thatstart the earliest for a given subframe. This may be done without takinginto account transmissions of the other CG that may overlap in time fora subsequent subframe, for example, when the WTRU is not capable of lookahead. This may relate in particular to PCM2 as further describedherein.

Additionally, guaranteed power may also be available as a minimum.SRS_(X) for CG_(X) may be from 0 up to max [P_(XeNB), P_(CGx)(PUSCH/PUCCH)]

In another example, the WTRU may also allocate power to SRStransmission(s) at most up to the guaranteed power for the CG when theamount of power allocated to PUCCH/PUSCH transmissions of the same CGfor the same subframe is less than the guaranteed power (including thecase where no power is allocated to PUCCH/PUSCH transmissions).

In particular for PCM1: In an example, the WTRU may perform suchallocation of power for a specific power control method, e.g. such asfor a power allocation method where any remaining power may be allocatedto transmission(s) of the group of cells (or CG, or MAC instance) bytaking into account transmissions of the other CG and that may overlapin time for a subsequent subframe e.g. the WTRU is capable of lookahead.

SRSx for CGx may be from 0 up to max [P_(XeNB), P_(CMAX)-P_(CGy)]:

In particular for PCM1: The WTRU may allocate any unused power in theother CG if the WTRU can determine the exact power requirements of anypossible overlapping transmissions at least ahead of the transmission ofthe SRS (e.g. the WTRU is capable of look-ahead).

For example, the WTRU may perform the following:

-   -   The WTRU may first determine the desired amount of power for the        SRS transmission(s) of the CG, using applicable power control        formulas for SRS e.g. as per legacy methods; (SRS_(X) for CG_(X)        may be from 0 up to max [P_(XeNB), P_(CMAX)-P_(CGy)]);    -   The WTRU may determine that the maximum amount of power that can        be allocated to the SRS transmission(s) for the CG is the        maximum between the guaranteed power of the associated CG and        the maximum available power (e.g. P_(CMAX)) less the allocated        power of the other CG (e.g. P_(CGy));    -   If the WTRU determines that the desired power is more than the        maximum amount of power available for SRS, the WTRU may either        drop or scale the SRS transmission(s). The scaling may be        performed according to legacy methods for SRS scaling.

In one example, the WTRU may allocate power to SRS transmission(s) of aCG at least up to the sum of the guaranteed power for the CG and anyportion of the remaining power used by PUCCH/PUSCH for the same CG.

The WTRU may possibly perform the above power allocation method for SRStransmission(s) only if the WTRU perform PUSCH/PUCCH transmission(s)associated to the same CG and for the same subframe.

The WTRU may possibly perform such power allocation function dependingon the type of trigger for SRS. For example, the WTRU may perform theabove power allocation function for aperiodic SRS transmissions (as suchSRS request are typically associated with a grant for an uplinktransmission e.g. PUSCH).

Processing Time Budget: The difference in timing between transmissionsof each CG may impact the time available to the WTRU to process receivedscheduling information and the time available to perform powerallocation, prioritization and other tasks required to determine one ormore parameters of all transmissions for a given subframe in case atleast one transmission is required in each CG for the concernedsubframe.

In particular, this may be a challenge for WTRU implementations whensuch methods require that a certain amount of processing is completedfor transmissions related to both CGs such that all transmissionsapplicable for the WTRU in the concerned subframe may be considered,e.g. such as for power allocation that dynamically allocates parts ofthe total WTRU available power across CGs or across all transmissions ofthe WTRU. In addition, different WTRU s may have different capabilitiesin terms of how fast it can process such information.

Different methods may differ in terms of how they threat timingdifferences between Tx. For example, different methods (such asprioritization functions, power allocation methods or scaling methods)such as those described herein may operate for a subset of transmissions(e.g. such as transmissions that all start simultaneously or within acertain time) either with or without consideration for transmissionsthat may start at a different time and that may be overlapping with eachother in time.

Start time of transmissions from perspective of processing timereduction: With respect to WTRU processing time, examples of overlappingtransmissions that start simultaneously include transmissions associatedto the same CG and/or to the same Timing Advance Group (TAG). Examplesof overlapping transmissions that start near-simultaneously within acertain time include transmissions associated to the same CG butpossibly to different TAGs, or transmissions associated to different CGsbut using the synchronized mode of uplink operation. Examples ofoverlapping transmissions that occur at different time includetransmissions associated to different CGs when using the asynchronousmode of uplink operation.

A WTRU may thus determine what function or method to apply as a functionof its determination of the available processing time. For example, ifthe WTRU determines that the available processing time is insufficientdue to its estimation of the difference in timing for transmissionsassociated to the same subframe across CGs then the WTRU may perform afirst method; otherwise if sufficient the WTRU may perform a secondmethod. A first method may be a method that considers all transmissionsfor the WTRU for the concerned subframe while the second method mayconsider the required power of a first subset of the WTRU'stransmissions only (e.g. those of a single CG, such that thosetransmissions occur earliest for the concerned subframe) and anothervalue for the required power of the second subset of the WTRU'stransmissions e.g. a minimum guaranteed value for transmissions of theother CG.

Available processing time, processing time reduction and threshold:Similarly as described in the previous section, the WTRU may apply afirst prioritization function (e.g. a power allocation method and/or ascaling function) when it determines that uplink operation betweenconfigured CG's may lead to a time budget for the WTRU's processing thatis below a certain threshold, and that it may apply a secondprioritization function (e.g. a different power allocation method and/ora different method for the scaling function) otherwise. Equivalently,the WTRU may estimate the reduction in available processing time budgete.g. when comparing between the processing time with or without dualconnectivity being configured and determine what method to useaccordingly.

Minimum Required Processing Time: For example, the WTRU may consider asa threshold a minimum required WTRU processing time. Alternatively, theWTRU may equivalently consider a maximum processing time reduction.

Such threshold may be specified as a fixed value and/or may be part ofthe WTRU's capability. Alternatively, it may be implementation specificand only known to the WTRU. In the latter case, the selection of themethod to be used by the WTRU to perform prioritization, powerallocation and/or power scaling may be entirely up to the WTRUimplementation.

Example definitions of processing time: The WTRU may define the quantityused in the comparison between required and available processing timeaccording to any of the following, without precluding other definitions.

Time until all scheduling information can be known for both CGs.

In an example, processing time reduction may be defined as essentiallyequivalent to the difference in DL arrival time for schedulinginformation for each CG for a given subframe.

In one method, such processing time may represent the time required toreceive downlink control signaling (e.g. on PDCCH and/or E-PDCCH) and toprocess the received control information. In other words, it mayrepresent a quantity that include the earliest time (e.g. either firstsymbol of the subframe or first symbol of the control channel for thatsubframe) for which the WTRU may start receiving control signaling insubframe n across all cells of the WTRU's configuration, until the WTRUmay first determine all necessary parameters for all transmissions for agiven CG or for both CGs.

In this case, the processing time reduction may be equivalent to thedifference in DL timing between a subframe associated to the earliestTAG of the WTRU (e.g. from the earliest CG) and a subframe associated tothe latest TAG of the WTRU (e.g. from the latest CG).

In another example, processing time reduction may be defined asessentially equivalent to the difference in start UL subframe for eachCG for a given subframe.

In one method, the WTRU may determine that the processing time reductionis equal to the difference between the start of the UL subframe of theearliest TAG (e.g. for the earliest CG) and the start of the UL subframeof the latest TAG (e.g. for the latest CG) for the concerned subframe.Possibly, only based on Nta_ref i.e. using the timing alignment valuelast updated by network signaling for each concerned TAG.

In another example, processing time reduction may be derived based onmethods to determine whether the WTRU operates according to thesynchronous or asynchronous mode of UL operation.

In one method, the WTRU may determine the reduction in processing timeusing a method described herein, for example regarding synchronous andunsyncrhonous uplink transmissions across CGs.

In another example, processing time may be defined as a time from end oflast (E-)PDCCH reception until all scheduling information can be known.

In another example, processing time reduction would be essentiallyequivalent to the difference in DL arrival time for schedulinginformation for each CG for a given subframe.

In one method, such processing time may represent the processing timerequired to determine all parameters necessary to apply a prioritizationfunction, such as performing power allocation and/or power scaling, oncethe control channels that occur last in time has been received.

In another example, processing time may be defined as time left forpower allocation/scaling once all scheduling information is known forboth CGs.

In one method, such processing time may represent the time budgetrelated to the processing required to perform a prioritization function,such as performing power allocation and/or power scaling, for example,once the WTRU has already determined all parameters necessary to performthe prioritization function.

In another example, processing time may be essentially equivalent totime between DL arrival time for scheduling information of latest CG ina given subframe n and start of UL subframe of earliest CG in subframen+4.

In one method, such processing time may be determined as time from theend of a subframe n on which the WTRU may receive control signaling forthe latest TAG (e.g. for the latest CG) and the time of the start of theUL subframe for the earliest TAG (e.g. for the earliest CG) in subframen+4.

Methods to determine available processing time budget: In some methods,the WTRU may consider only a TAG with at least one activated cell.Alternatively in some methods, the WTRU may consider any cell of itsconfiguration, independently of activation state. In some methods, theWTRU may further consider only a cell that is used as a DL timingreference e.g. when the WTRU determines a parameters as a function of adownlink component (e.g. timing of reception of control signaling, startof DL subframe or the likes).

Methods to determine the available processing time budget: The WTRU maydetermine the available processing time budget and compare it to theminimum required WTRU processing time (i.e. a threshold). The WTRU maydetermine the available processing time based on the principlesdescribed above for the definition of the processing time. Details ofsuch method are further described below.

Time reduction as difference in uplink timing: For example, the WTRU maydetermine that the reduction in available processing time is equal tothe timing difference of uplink subframe for each CG e.g. according toany of the method described herein, including with respect tosynchronous and unsynchronous uplink transmissions across CGs.

Available processing time: For example, the WTRU may determine theavailable processing time based on the time between a “DL timingcomponent” and an “UL timing component.” For example, such DL timingcomponent may be related to reception of downlink signal. Such downlinksignal may comprise downlink signaling information for scheduling of anuplink transmission for a first CG (e.g. downlink control signalingreceived in subframe n). Such UL timing component may be related to atransmission of a signal in the uplink. Such uplink transmission maycomprise an uplink transmission for the corresponding subframe for asecond CG (e.g. subframe n+4).

First CG may be the later CG—i.e. latest Downlink component for subframen: For example, the first CG may be the CG for which the WTRU determinesthat the start of a downlink subframe n occurs later than that of thecorresponding subframe n for the other CG. Possibly, only for theapplicable Timing Advance Group (TAG) and/or cell for the respective CG.For example, such TAG may be the TAG that includes the special cell ofthe CG (e.g. the cell configured with PUCCH resources and/or the cellthat is always active).

Second CG may be the earlier CG—i.e. earlier Uplink component forsubframe n (or n+4): For example, the second CG may be the CG for whichthe WTRU determines that the start of an uplink subframe (ortransmission for subframe) n occurs earlier than that of thecorresponding subframe n for the other CG. Possibly, only for theapplicable Timing Advance Group (TAG) and/or cell for the respective CG.For example, such TAG may be the TAG that includes the special cell ofthe CG (e.g. the cell configured with PUCCH resources and/or the cellthat is always active).

DL timing component: For example, a DL timing component may be based onsignaling such as a DCI received on PDCCH (or E-PDCCH) for the CG. Forexample, such timing of the downlink signaling may be one of Start/endof the subframe in which DCI is received; Start/end of the PDCCH onwhich DCI is received; Start/end of PDCCH decoding process for thereceived DCI; or End of processing of received DCI; as in the following:

Start/end of the subframe in which DCI is received: The time of thefirst (or last) symbol of the subframe of the cell of the CG thatcorresponds to the downlink resources on which the WTRU received thesaid control signaling. Similarly, the WTRU may use the DL timingestimation for the corresponding cell (or Timing Advance Group).

Start/end of the PDCCH on which DCI is received: The time of the first(or last) symbol of the PDCCH (or E-PDCCH) on which the said controlsignaling is received.

Start/end of PDCCH decoding process for the received DCI: The time atwhich the WTRU may start attempts to decode the said control signalingor, alternatively, the time at which the WTRU may successfully decodesthe said control signaling.

End of processing of received DCI: The time at which the WTRU hascompleted processing of the said control signaling. For example, thismay correspond to the time instant at which the WTRU has all thenecessary information to calculate the power for all transmissions of aCG.

“UL timing component:” For example, such UL timing component may bebased on the start of a transmission for the CG.

Example realizations of estimation of available processing time aredisclosed in greater detail hereafter.

Start of latest PDCCH until start of earliest UL subframe: In oneexample of the above methods, the WTRU may first determine that is has aminimum required processing delay when operating with dual connectivity.Such processing delay may represent the delay from the time it startsreceiving the latest occurrence of a PDCCH in subframe n across any ofthe configured (and possibly activated) serving cells of itsconfiguration up to the time it is required to perform the firsttransmission across any of the (possibly activated) serving cells withconfigured uplink in subframe n+4. The WTRU may then determine that itis expected to perform at least one uplink transmission in each of theconfigured CGs in subframe n+4; such may include any combination ofPUSCH, PUCCH, SRS or PRACH transmissions. The WTRU may determine theavailable time budget and compare it with the minimum requiredprocessing time.

Completion of decoding of all PDCCH until start of earliest UL subframe:In another example of the above methods, the WTRU may first determinethat is has a minimum required processing delay when operating with dualconnectivity. Such processing delay may represent the delay from thetime it has successfully completed decoding of all PDCCH occurrences insubframe n across any of the configured (and possibly activated) servingcell of its configuration up to the time it is required to perform thefirst transmission across any of the (possibly activated) serving cellswith configured uplink in subframe n+4. The WTRU may then determine thatit is expected to perform at least one uplink transmission in each ofthe configured CGs in subframe n+4; such may include any combination ofPUSCH, PUCCH, SRS or PRACH transmissions. The WTRU may determine theavailable budget and compare it with the minimum required processingtime.

Start/end of latest subframe until start of earliest UL subframe: Inanother example of the above methods, the WTRU may first determine thatis has a minimum required processing delay of x milliseconds (ms) whenoperating with dual connectivity. Such processing delay may representthe delay from the start (or the end) of the subframe of the servingcell(s) that starts latest in time in subframe n across any of theconfigured (and possibly activated) serving cells of its configurationup to the time it is required to perform the first transmission acrossany of the activated serving cells with configured uplink in subframen+4. The WTRU may then determine that it is expected to perform at leastone uplink transmission in each of the configured CGs in subframe n+4;such may include any combination of PUSCH, PUCCH, SRS or PRACHtransmissions. The WTRU may determine the available budget and compareit with the minimum required processing time.

In another example of the above methods, the WTRU may be required toperform a PRACH transmission (or retransmission) following reception ofcertain DL control signaling or after the end of a random accessresponse window. For instance, the WTRU may be required to transmit (orretransmit) PRACH following reception of a “PDCCH order,” followingreception of a random access response that does not contain a responseto a previously transmitted preamble sequence, or if no random accessresponse is received in the last subframe of the random access responsewindow.

The WTRU may determine a minimum processing time threshold correspondingto the duration between the end of the subframe in which PRACHtransmission or retransmission is triggered in a first cell group (e.g.the subframe in which PDCCH order is received, or a random accessresponse is received, or the last subframe of the window), and the startof the first subframe s0 in which the WTRU is required to be ready totransmit a preamble if a PRACH resource were available in this subframe.In case a transmission initiated in a second cell group before the startof subframe s0 overlaps with PRACH of the first cell group transmittedin subframe s0, i.e. when the available processing time is lower thanthe minimum, the WTRU may prioritize the transmission of the second cellgroup over the PRACH transmission of the first cell group. In case atransmission initiated in a second cell group overlaps with PRACH of thefirst cell group transmitted at least one subframe after subframe s0,and the transmission of the second cell group did not start more thanone subframe before PRACH, i.e. when the available processing time ishigher than the minimum, the WTRU prioritizes the PRACH transmission ofthe first cell group over the transmission of the second cell groupunless the latter is another PRACH transmission of higher priority, suchas PRACH of Pcell. Stated differently, the WTRU may prioritize PRACH ofa first cell group over another transmission of a second cell group ifthe transmission timing of PRACH (in subframe s1) is such that the WTRUis ready to transmit the PRACH at least one subframe before thissubframe (i.e., in subframe s1-x, where x>=1) and provided that thetransmission of the second cell group does not start earlier than 1subframe before the PRACH of the first cell group and is of lowerpriority rank.

Different WTRU behaviors depending on available processing time: For allexamples above, the WTRU may further determine that power should beallocated to transmissions of the CG that occurs first by consideringthat a specific amount of power should be reserved to transmissions ofthe other CG (e.g. a semi-static, possibly configured, value such that aminimum guaranteed amount of power may be allocated to that CG) if theavailable processing time is insufficient; in other words, the WTRU maynot be not mandated to consider the power required for the actualtransmissions for that CG and may subsequently perform scaling of thepower for one or more transmissions for that CG in case the allocatedamount of power is less than the amount required. Otherwise if theavailable processing time is sufficient, the WTRU may further determinethat power should be allocated to transmissions of the CG that occursfirst by considering the power required for transmissions of the otherCG; if the total amount of power required exceed the maximum availablepower of the WTRU, the WTRU may perform scaling of power across alltransmissions of the WTRU using any of the prioritization methodsdescribed herein.

Triggers are disclosed in greater detail hereafter to perform estimationof available processing time.

When to determine available processing time: For all examples above, theWTRU may determine the available processing time when at least one ofthe following events occur: Periodic events, Reconfiguration events,Gaining timing alignment events, Updating timing alignment events, orOverlapping transmission events as described in the following:

-   -   a. Periodic events: When a timer expires, e.g. periodically. The        WTRU may restart such timer once it has determined and/or        updated the available WTRU processing time.    -   b. Reconfiguration events, i.e., reconfiguration that may        indicate that timing characteristics of one or more configured        serving cell(s) have changed: Subsequent to a RRC        reconfiguration that adds or remove at least one timing advance        group (TAG) from the WTRU's configuration. This may include        initial configuration of a SCG, initial addition of at least one        cell to a TAG or the likes.    -   c. Gaining timing alignment events, i.e., when gaining UL timing        alignment for a TAG: When the WTRU performs a procedure        following which the WTRU has a valid timing alignment for a TAG,        e.g. upon applying a received TAC in a RAR in the random access        procedure, upon receiving a MAC TAC CE and/or when restarting at        least one TAT that was previously expired.    -   d. Updating timing alignment events, i.e. when updating UL        timing alignment for a TAG: When the WTRU receives a MAC TAC for        a TAG, e.g. upon applying a received TAC in a RAR in the random        access procedure, upon receiving a MAC TAC CE and/or when        restarting at least one TAT.

Overlapping transmission events, i.e. when it determines that at leastone uplink transmission may be performed for each CG in a givensubframe. When the WTRU determines that overlapping transmissions mayoccur in a given subframe n+4, e.g. after completion of processing of DLcontrol signaling for subframe n.

Further Example Realizations:

The WTRU may determine to allocate power with look ahead if processingtime budget is sufficient, and with guaranteed power otherwise. Forexample, the WTRU may determine that it should perform power allocationaccording to a first method when it determines that processing timereduction is below a certain threshold and according to a second methodotherwise. For example, the first method may be based on a determinationof the power allocated to each CG by considering required power for eachCG, while a second method may be based on a determination of the powerallocated to each CG based on the required power for the CG for whichtransmissions start earliest in time and based on a guaranteed amount ofpower for the other CG.

For the first method, the WTRU may perform power allocation and/or powerscaling per CG (e.g. per CG allocation) or across all transmissions ofthe WTRU (e.g. flat scaling) e.g. according to a method describedherein. For the second method, any remaining power not used fortransmissions of the earliest CG may then be allocated to the other CG.

The WTRU may determine to perform power scaling using flat scaling ifprocessing time budget is sufficient, and on the power for a CGotherwise. For example, the WTRU may determine that it should performpower scaling according to a first method when it determines thatprocessing time reduction is below a certain threshold and according toa second method otherwise. For example, the first method may be based onscaling transmissions by considering all transmissions across both CGsaccording to priority between such transmissions (e.g. by type), while asecond method may be based on scaling power per CG e.g. by firstallocating power per CG and then performing scaling across transmissionsof a given CG only.

Additional power sharing methods between transmissions of different MACinstances are further discussed herein. In some implementations, theWTRU may allocate power to transmissions associated to different MACentities (hereafter a “cell group” or “CG”) in a given subframe suchthat a first amount (or fraction e.g. P_(MeNB)) of the total WTRUavailable power (e.g. P_(CMAX)) is reserved to transmissions of a firstCG (“Primary CG”, or “MCG”), and a second amount (or fraction e.g.P_(seNB)) of the total WTRU available power (e.g. P_(CMAX)) is reservedto transmissions of a second CG (“Secondary CG”, or “SCG”). If the sumof P_(MeNB) and P_(seNB) is less than the total available transmissionpower P_(CMAX) the WTRU may also allocate the remaining power accordingto specific priority rules between CGs and/or between transmissionsassociated to each CGs.

It is noted that a MAC entity (or MAC instance) may be configured withone or more serving cells which may then form a Cell Group (CG). For theMAC instance or the CG that is associated to serving cells of a firsteNB (e.g. the MeNB), such may be referred to as the Primary CG (PCG) orthe Master CG (MCG); in this case, the concerned first MAC entity mayalso be referred to as the Primary MAC entity. Similarly, the MACinstance or the CG that is associated to serving cells of a second eNB(e.g. the SeNB) may be referred to as the Secondary CG (SCG) or the SeNBCG (SCG); in this case, the concerned second MAC entity may also bereferred to as the Secondary MAC entity.

The WTRU may perform such allocation of power according to a specificpower control mode (“PCM”), where the applicable PCM may be signaled aspart of the WTRU's configuration for dual connectivity operation.

For example, the WTRU may apply a first PCM (“PCM1”) (if configured)such that it may share any of the remaining power across transmissionsassociated to different CGs according to a prioritization determinedbased on the type of UCI associated to the different transmissions. TheWTRU may apply a second PCM (“PCM2”) (if supported by the WTRU and ifconfigured) such that it may reserve P_(MeNB) and P_(seNB) fortransmissions associated to the corresponding CG (e.g. MCG, and SCGrespectively) if there is a potential overlapping uplink transmission.The WTRU may first make available all remaining power to thetransmission(s) of the CG associated with the transmission(s) that areearlier in time.

The WTRU may determine whether or not it may perform additional sharingof power between CGs, including whether or not some (or all) of theguaranteed power of a second CG may be allocated to the transmissions ofa first CG.

In one example, the WTRU may determine whether or not there is at leastone transmission for the second CG, i.e. whether or not the requiredpower for the second CG is zero for the concerned transmission timeinterval and/or for the overlapping part in time between CGs (hereafter“subframe”). Such determination may be performed according to at leastone of semi-static aspects, dynamic aspects, or a WTRU-autonomousdetermination.

Semi-static aspects may include aspects related to L3/RRC configurationsignalling. For example, the WTRU may perform such determinationaccording to at least one of subframe type or subframe blanking.

Regarding determination according to subframe type i.e. whether thesubframe is for uplink transmissions or for downlink reception only, thedetermination may be based at least one of frame structure type, UL/DLconfiguration, or half-duplex operation,

Regarding determination based on frame structure type (e.g. type 1 FDDor type 2 TDD), for example, the WTRU may be configured with a cell forTTD operation. Possibly, a CG may be configured such that all cells ofthe CG are for TDD operation.

Regarding determination based on UL/DL configuration e.g. for TDD, forexample, the WTRU may be configured with a TDD UL/DL configuration. Suchconfiguration may be common to all cells with configured uplinkresources of a given CG. In this case, the WTRU may determine that nouplink transmission is expected for the CG in a DL-only given subframe.

Regarding determination based on half duplex operation e.g. for FDD, forexample, the WTRU may report half-duplex-only capability for a givensupported band. A CG may be configured such that all cells of the CGcorrespond to such band. In this case, the WTRU may determine that nouplink transmission is expected for the CG in a given subframe if atleast one downlink transmissions is expected in the concerned subframe.For example, the WTRU may make such determination for a subframe forwhich the WTRU is configured with a downlink assignment. The WTRU maymake such determination for a subframe for which the WTRU is required tomonitor PDCCH e.g. for reception of system information, paging (fornotification of update to system information) or the like.

Regarding determination according to subframe blanking, for example, theWTRU may be configured by L3 such that one (or more) type(s) oftransmissions is not possible for some subframes. In this case, the WTRUmay determine that no uplink transmission is expected for the CG in thesubframe.

Regarding determination according to periods of absolute priority in apower allocation period (e.g. for multi-RAT), for example, the WTRU maybe configured such that transmissions associated to a specific MACentity have absolute priority for one (or more) periods (or TTIs) withina configured power allocation period. Such period(s) with absolutepriority may be L3 configuration aspect, and/or may be determined basedon dynamic aspects such as L1/L2 control signaling as described in othersections. In this case, the WTRU may determine that no uplinktransmission is expected for the CG in the corresponding powerallocation period.

Dynamic aspects may include aspects associated with scheduling activityand related signalling. For example, the WTRU may perform suchdetermination according to at least one of DRX operation, RRC procedure,Timing Alignment, or Enhanced Interference Mitigation and TrafficAdaptation (“eIMTA”) UL/DL configuration.

Regarding determination according to DRX operation, the WTRU may beconfigured with a DRX pattern and related parameters. Such pattern mayrepresent the time during which the WTRU may be scheduled fortransmissions (e.g. DRX Active Time). Such DRX Active Time may includean On-Duration period, which occurs periodically and which has a fixedlength. Such DRX Active Time may be further controlled by the receptionof downlink control signaling such that the DRX Active Time may beextended (e.g. by scheduling activity) or stopped until the start of thenext On-Duration period (e.g. by reception of a MAC DRX CE). Such DRXpattern and Active Time may differ between CGs. Determination of suchDRX patterns and Active Time (or equivalent) may differ between CGs whenconfigured with different radio access technology. In an example, theWTRU may determine that no uplink transmission is expected for the CGfor subframe(s) during which the WTRU knows that it is not part of DRXActive Time. In another example, the WTRU may determine that no uplinktransmission is expected for the CG for a subset of subframe(s) duringwhich the WTRU knows that it is not part of DRX Active Time. This may beonly for such subframe for which the WTRU knows with absolute certainty,e.g. such as for the period that starts a certain amount of processingtime following the last subframe of the DRX Active Time such that theDRX Active Time cannot be extended in the last few subframes of the DRXActive Time and/or such as the period that start after the reception ofa MAC DRX CE. In both cases, the period may extend until the start ofthe next On-Duration period or until the WTRU triggers a SR (possiblyeven up to n+7 subframes following the transmission of the first SR fora given SR trigger).

Regarding determination according to RRC procedure and relatedinterruption, the WTRU may initiate a L3/RRC procedure that leads to aninterruption of the radio front end associated to transmissions for oneof the CGs only. For example, the WTRU may receive a RRC ConnectionReconfiguration message and initiate the reconfiguration of a CG. Insuch case, the WTRU may be allowed to not be active in transmissions forup to a certain amount of time, e.g. for 15 ms following the successfulreception of the RRC PDU. In this case, the WTRU may determine that nouplink transmission is expected for the CG during that time. The WTRUmay for example determine that no uplink transmission is expected forthe CG while timer T304 s is running. The WTRU may start T304 s when itreceives the RRC Connection Reconfiguration message with the mobilitycontrol information element that modifies the SCG. The WTRU maydetermine that no uplink transmission is expected for the CG when itdeclares RLF for the CG. For example, the WTRU may determine that RLFhas occurred on the SCG and declared S-RLF, which stops all uplinktransmissions for the SCG until the WTRU receives a reconfiguration thatmodifies the SCG.

Regarding determination according to maintenance of timing alignment(synchronization state), the WTRU may determine that no uplinktransmission is expected for the CG when a Timing Alignment Timer (TAT)associated to the primary Timing Advance Group (pTAG) and/or associatedto the special cell of the CG (e.g. the PCell for the MCG, and thePSCell for the SCG) is not running. WTRU may additionally determine thatno uplink transmission is expected for the CG between the subframe inwhich the WTRU starts or restarts the TAT of the pTAG for the CG anduntil the first occasion for an uplink transmission. For example, if theTAT is restarted from the reception of a RAR that includes a TAC and agrant for an uplink transmission in subframe n, the WTRU may determinethat no uplink transmission is expected for the CG until subframe n+xwhere x is the allowed processing time (x may be equal to 6 ms, forexample). This may thus include the time during the RAR window (timewhile RA Response Timer is running) as well as the time from thereception of the first grant in the RAR up of the subframe for the firstPUSCH transmission with this grant.

Regarding determination according to eIMTA uplink/downlinkconfiguration, the WTRU may determine that no uplink transmission isexpected for the CG based on the outcome of the procedure fordetermining the eIMTA-uplink/downlink configuration. Such determinationmay take place based on the reception of PDCCH scrambled by a specificRNTI (eIMTA-RNTI) in a previous subframe, or the absence of receptionthereof, as well as higher layer information.

WTRU autonomous determination may relate to implementations where theWTRU may perform such determination according to at least one of S-RLF,WTRU capabilities exceeded, in-device coexistence (IDC) or otherimpairment situations.

Regarding determination according to S-RLF, the WTRU may determine thatno uplink transmission is expected for the CG when it declares RLF forthe CG. For example, the WTRU may determine that RLF has occurred on theSCG and declared S-RLF, which stops all uplink transmissions for the SCGuntil the WTRU receives a reconfiguration that modifies the SCG.

Regarding determination according to exceeded WTRU capabilities, theWTRU may determine that no uplink transmission is expected for the CGwhen it determines that one or more of its capabilities are exceeded fora given period and/or subframe.

Regarding determination according to In-Device Coexistence (IDC), a WTRUmay autonomously ignore a grant and/or drop a transmission if it hasoverlapping transmissions for another radio technology or otherreception such as GPS that could be disrupted, if such transmission(s)would otherwise interfere with possibly critical transmissions of theother radio technology. Such behavior may affect transmissions of asingle CG, e.g. the CG operating in the same frequency band as the otherradio technology. Such behavior may also be conditioned by a patternknown to the WTRU e.g. in case of predictable traffic. In such case, theWTRU may determine that no uplink transmission is expected for the CGwhen such overlap occurs.

Regarding determination according to other impairment situations, theWTRU may determine that no uplink transmission is expected for the CGwhen an impairment situation that precludes one or more transmissions(or all) for a CG occurs for a given subframe.

The WTRU may allocate some or all of the guaranteed power of the secondCG to transmissions of the first CG when it determines that there is notransmission associated to the second CG for the concerned subframeand/or overlapping period. In some implementations, the WTRU may performsuch reallocation of at least part of the guaranteed power of the secondCG only if it also determines that the similar condition is alsodetermined for transmissions of the second CG in the subsequent subframeand/or overlapping period. For example, the WTRU may perform suchreallocation of the guaranteed power of the second CG only if it alsodetermines that there is no transmission expected for the second CG inthe subsequent subframe and/or overlapping period.

It may be determined whether or not the power required is within aspecific range. For example, in one method the WTRU may determinewhether or not the transmission power required for the second CG in agiven subframe may be equal or below a certain threshold (but possiblynon-zero).

In some implementations the WTRU may perform such determination byconsidering only specific type(s) of uplink transmissions. For example,the WTRU may perform such determination using the above methods but onlybased on PUSCH transmissions, such that the WTRU may determine that thetotal power required for PUSCH is zero. In some implementations, theWTRU may perform such determination also including any possible PRACHtransmission. Further determination may be based on other type(s) oftransmission and/or of UCI type(s), e.g. PUCCH for ACK/NACK, CQI, SR orSRS. Such further determination may be based on the exact powerrequirement(s) of the CG for the concerned subframe, or based on aprobabilistic assessment (e.g. based on previous transmission levels forsimilar transmissions and/or by taking into account a certain margin oferror). Such threshold may correspond a level that is below the value ofguaranteed power for the CG (hereafter P_(xCG)). Possibly, suchthreshold may correspond to the value of P_(xCG) applicable to theconcerned subframe less a certain margin of error. Such margin of errormay correspond to the maximum open loop adjustment expected for a givenperiod of time. Possibly, this corresponds to the maximum step unit forsuch open loop adjustment.

Such further determination may be performed according to at least one ofUE-autonomous transmission or retransmission, data available fortransmission, Scheduling Request (SR) pending, last reported BSR, or L2configuration, including DRB type.

Regarding determination according to UE-autonomous transmission orretransmission, such transmission types may include a configured uplinkgrant such that all parameters of a PUSCH transmission may be known fora subframe n+4, a WTRU-autonomous non-adaptive retransmission for anongoing HARQ process that has not yet completed successfully, and/or adownlink configured grant such that all parameters of a possible PUCCHtransmission (for HARQ ACK/NACK feedback) may be known for subframe n+8,where subframe n is the scheduling occasion corresponding to thescheduling (i.e. possibility to adapt) occasion for the PUSCH or thePDSCH transmission, respectively. In this case, the WTRU may determinethe power required by such transmissions in advance of their relativescheduling occasion in subframe n if it may also determine that no othertransmissions may be scheduled (or required), for example based on othermethods as described herein and including the case where the subframe inquestion corresponds to the scheduling occasion (e.g. subframe n) suchthat the concerned transmissions or retransmissions may be performed butmay not be adapted. This may also be applicable for any HARQ processesthat are suspended and that may not be restarted such that the WTRU isnot expected to perform an autonomous non-adaptive retransmission in theconcerned subframe (i.e. the WTRU may determine that zero power isrequired for such processes).

Regarding determination according to data available for transmission,the WTRU may determine that there is no data available for transmissionfor a given subframe for a given CG, such that reception of a grantwould lead to transmission of padding information or no transmission atall. In this case, the WTRU may determine that zero power is requiredfor PUSCH for the CG in the concerned subframe, although othertransmissions may be possible.

Regarding determination according to whether a scheduling request (SR)is pending, The WTRU may determine that it has triggered a SR. In thiscase, the WTRU may determine that no PUSCH transmission(s) are expectedfrom the time the WTRU triggers the SR until the time it may firstreceive a grant for an uplink transmission e.g. at least until thesubframe of the initial transmission of the SR and possibly up to acertain (eNB) processing time after (e.g. 3 ms). The WTRU may howevertake into account the (exact, or maximum possible) power required for SRon PUCCH (if applicable) or the power required for one or more preambletransmissions or retransmissions (otherwise) for the applicable subframe(D-SR occasion or PRACH occasion, respectively) during this interval. Insome implementations the WTRU may consider this aspect only if the SRwas triggered due to new data becoming available for transmission whilethe WTRU's buffers for radio bearers (or LCH) associated to the CG werepreviously empty.

Regarding determination according to a last reported BSR, the WTRU maydetermine that it last reported a certain amount of data in its buffersand determine from this that it may no longer receive grants for uplinktransmission that would be useful for transmission of any data forbearers associated to a given CG. For example, the WTRU may have lastreported empty buffers, e.g. by including a padding BSR in the lastuplink transmission, possibly only if no new data has been madeavailable for transmission for the CG since the last transmission of aBSR. In this case, the WTRU may determine that no PUSCH transmission(s)are expected for a given subframe during which this condition may betrue.

Regarding determination according to L2 configuration, including DRBtype, the WTRU may determine that it is configured such that no userplane traffic may be transmitted using resources of the CG. In thiscase, the WTRU may determine that no PUSCH transmission or transmissionsare expected for the CG for a given subframe.

For example, the WTRU may determine that the SCG is configured only witha split DRB (for the downlink) such that the uplink path is mapped onlyto the other CG i.e. the MCG. In this case, only L2 control PDUs may becarried on PUSCH, if any. For example, the WTRU may be configured withsplit DRBs (e.g. DRBs that are associated to both CGs at least fordownlink traffic) and without SCG-only DRB. In this case, if the WTRU isadditionally configured such that a single uplink path (or CG) may beused for transmission of user plane data (e.g. PDCP PDUs) and this CG isthe MCG, then the WTRU may determine that no user plane data is expectedto be transmitted using uplink resources of the SCG. The WTRU maydetermine that PUCCH, SRS, PRACH may be expected while for PUSCH onlytransmissions using small transport blocks (e.g. containing RLC controlPDUs) may be expected sporadically at times known by the WTRU. Forexample, the WTRU may be configured with split DRBs (e.g. DRBs that areassociated to both CGs at least for downlink traffic) and withoutMCG-only DRBs. In this case, if the WTRU is additionally configured suchthat a single uplink path (or CG) may be used for transmission of userplane data (e.g. PDCP PDUs) and this CG is the SCG, then the WTRU maydetermine that no user plane data is expected to be transmitted usinguplink resources of the SCG. The WTRU may determine that PUCCH, SRS,PRACH may be expected while for PUSCH only transmissions using smalltransport blocks (e.g. containing RLC control PDUs) or transmissionscontaining SRB data may be expected, both sporadically at times known tothe WTRU.

In another example, the WTRU may determine that it is not expected toperform any transmission of a specific type using uplink resourcesassociated to a specific CG. For example, the WTRU may determine that itis not expected to perform any PUSCH transmission (e.g. such that onlyPRACH, PUCCH, SRS may be possible). For example, the WTRU may determinethis based on the level of data available for UL transmission in theWTRU's buffer associated to this CG. For example, the WTRU may determinethat it has no data available for transmission for this CG or otherwisethat such nonzero amount of data can be served by granted resourcesalready known to the WTRU and applicable to a different subframe. Forexample, the WTRU may also determine that any PUCCH/SRS would not exceeda certain amount within the guaranteed power (PL estimate, fewsemi-static parameters e.g. PUCCH format). Such determination may bepossible because the information that may not be available to the WTRUmay only cause an error in the setting of the power up to a maximumthreshold e.g. such as 3 db in case of a TPC command, which error may beaccounted for in the setting of the transmission power. For example, theWTRU may also determine the power setting for a Periodic SRStransmission in advance as the setting of the power for suchtransmission is based on a semi-static configuration. For example, theWTRU may also determine whether or not power is required for anAperiodic SRS transmission using similar methods as for determinationfor PUSCH transmission, because the request for an Aperiodic SRStransmission is typically received together with a grant for a PUSCHtransmission. In other words, the WTRU determines that it is notexpected to transmit an Aperiodic SRS when it determines that it is notexpected to perform a PUSCH transmission e.g. using methods describedherein. In some implementations the WTRU may determine an upper boundfor all transmissions of the CG for a given subframe, based on suchdeterminations as described above. Such upper bound may be a function ofthe estimated path loss and/or the format of the transmissions for theconcerned subframe or the like (e.g. PUSCH format.)

The WTRU may allocate some or all of the guaranteed power of the secondCG possibly up to a value equal to the applicable threshold less thecalculated or estimated amount or required power for transmissions ofthe second CG. Such power may be reallocated to transmissions of thefirst CG. In some implementations, power may be reallocated totransmissions of the first CG only if the required power for a specifictype of transmission is equal (or at least expected to be equal) to zeroe.g. there are no PUSCH transmissions for the second CG.

In some implementations the WTRU may perform such reallocation of atleast part of the guaranteed power of the second CG only if it alsodetermines that the similar condition is also determined fortransmissions of the second CG in the subsequent subframe and/oroverlapping period. For example, the WTRU may perform such reallocationof at least part of the guaranteed power of the second CG only if italso determines that at least the same level of reallocated power is notexpected to be required for transmissions of the second CG in thesubsequent subframe and/or overlapping period.

In one method, the WTRU may first perform such determination for a givensubframe by performing at least one of the following steps, possibly inthe order listed below:

-   -   1. The WTRU may first calculate the P_(CMAX) for the possible        overlapping part of the transmissions across both CGs;    -   2. The WTRU may then calculate power requirements for the second        CG;    -   3. If the (possibly, estimation of the) power required for the        second CG is less than the power corresponding to the guaranteed        portion of P_(CMAX), the WTRU may reallocate the unused part of        such portion to transmission(s) of the other CG.

In some implementations the WTRU may perform such determination onlywhen the WTRU is configured with PCM2. In some implementations the WTRUmay apply such determination only if the WTRU reports that it supportssuch capability. In some implementations the WTRU may apply suchdetermination only if the WTRU is explicitly configured to perform suchdetermination. In some implementations the WTRU may apply suchdetermination only such that it can reclaim some of the guaranteed powerof a second CG to the benefit of a first CG. For example, the first CGmay be the MCG always, or the CG that is associated to transmissionsthat occurs earliest in time for a given subframe. For example, thesecond CG may be the SCG always, or the CG that is associated totransmissions that occurs latest in time for a given subframe.

If the WTRU makes an incorrect determination such that schedulingrequires the WTRU to allocate more power to transmissions of a specificCG while the CG has insufficient power (including less power than theguaranteed amount) due to power reallocation according to the abovemethods for a given subframe, the WTRU may simply apply otherprioritization methods such as e.g. scaling within the reallocatedamount. In such case, the WTRU may refrain from such power reallocationin subsequent subframe(s). In some implementations the WTRU may refrainfrom such power reallocation until it determines that any impactedtransmission has succeeded and/or until the WTRU determines that it isnot power limited.

Additional signalling methods supporting scheduling cooperation arefurther discussed herein. Methods are described herein whereby the WTRUmay report certain aspects to one or more scheduling functions for thepurpose of improving cooperation between schedulers. Signalling methodsand other aspects described below may additionally apply to methodsdescribed in other sections herein. For example, happy bit indicationmay use similar signaling as described below. Similarly, signalingdescribed below may alternatively be combined with methods described inother sections herein.

In an example scenario for illustrating additional signalling methodssupporting scheduling cooperation, a WTRU may be associated with aspecific category in terms of its capabilities. Such capability mayinclude (but is not limited to) sustained data rate and processing e.g.in terms of number of soft buffer bits that can be handled (e.g.received and/or transmitted) in a given period of time (e.g. a TTI or asubframe). For example, a WTRU supporting LTE Carrier Aggregation with 2uplink carriers may support a Dual Connectivity feature with asynchronous mode of operation (e.g. PCM1 only) or both the synchronousand the asynchronous modes of operation based on their declaredcapabilities. Based on the WTRU's category, such WTRUs may thus have asimilar sustained data rate and processing capabilities.

When a WTRU is configured with more than one serving cell according toLTE CA, a single scheduler may drive the data rate and the schedulingopportunities. This may enable a well-defined DL/UL traffic flow thatcan be based on a WTRU declared category. In such a controlledenvironment, it may be expected that the WTRU will support its sustaineddata rates and that its processing capabilities should not be exceeded.

However, in a WTRU configured with more than one serving cell accordingto LTE Dual Connectivity, scheduling of the WTRU may involve independentschedulers operating in separate eNBs. The concerned eNBs may coordinate(e.g. using X2 signalling) a number of aspects related to the WTRU'scapability. Such aspects may include (but are not limited to) bufferdata split in downlink, buffer data split in the uplink, maximum numberof UL-SCH transport block bits transmitted in a TTI, maximum number ofDL-SCH transport block bits received in a TTI, and/or total availablepower in the form of UL power ratio between cell groups (e.g. P_(MeNB)and P_(SeNB)) for uplink transmissions. While the WTRU category isknown, the opportunistic scheduling in both MeNB and SeNB may lead to aWTRU processing overload, such that one (or more) of the WTRU'scapabilities might be exceeded. For example, the WTRU may experience asoft buffer shortage or may not have enough processing power to get itsphysical layer soft buffers released fast enough. Such situation mayarise and may eventually lead to other impairments that may furtherimpact the operation of the physical layer and/or the operation of otherprotocols such as L2 protocols (MAC, RLC, PDCP). For example, suchimpairment may include a failure to successfully complete an uplink HARQprocess which may in turn cause a RLF (for a primary MAC instance, MCG)or an interruption of all uplink transmissions with the trigger for anuplink notification (for a secondary MAC instance, SCG).

Methods are described below which may overcome such problems. Thefollowing described solutions may be used as standalone methods, incombination with each other, or in combination with other methodsdescribed in other sections, and include methods to determine animpairment condition, methods to signal an impairment condition, furthermethods for a condition related to uplink transmissions, and a triggerfor S-RLF.

Methods to determine an impairment condition are further discussedherein. For example, the WTRU may detect that at least one of itscapabilities are exceeded, and may initiate a procedure to signal suchcondition to the network (e.g. signaling towards either the MeNB, theSeNB or both). Such capabilities may include the total maximum number ofUL-SCH transport block bits transmitted in a TTI, the total maximumnumber of DL-SCH transport block bits received in a TTI, the totalamount of WTRU available power or more generally a threshold related toprocessing capabilities. Similarly, such signaling may be triggered whena condition related to QoS is not met, or similar.

The WTRU may initiate signaling of such a condition according to atleast one of the possible triggers: 1) a threshold being exceeded for acertain amount of time (a timer may set before triggering such that thestate has been sustained for a certain amount of time) or 2) a thresholdbeing exceeded in a specific CG, i.e. either the MCG or the SCG (atimer, e.g. one for each CG, may be envisioned here before triggeringsuch that the state has been sustained for some time).

In some implementations such indication may apply per MAC instanceand/or per CG. In some implementations such indication may apply perWTRU. Optionally, such indication may be per carrier and/or per servingcell.

Additionally, the above triggers may be linked through a DL/UL 2 bitcombination indicating the transmission direction of the processingissue that is being problematic.

In some implementations, either in combination with the above oralternatively to such signaling, the WTRU may apply any other configuredprioritization function during such period e.g. such as the use of oneor more alternative grant(s) as described herein.

Methods to signal an impairment condition are further discussed herein.Such methods may include specific values in CQI reporting, indicationson PUCCH or in UCI on PUSCH, indications using a CSI feedback process,indications using SR over PUCCH, and/or indications using MAC CEsignaling, as further discussed below.

When the WTRU initiates the signaling of an impairment condition, e.g.using triggers as described above or any other trigger, the WTRU may usesignaling as described below. Upon reception of such indication, theconcerned eNB may use a more conservative scheduling approach such aslowering the transport block size, scheduling less frequently or simplystop scheduling the WTRU e.g. until an indication that the condition isno longer valid. For example such indication may be a valid CQI value(i.e. CQI back in range) signaled by the WTRU.

In some implementations, the methods described to signal an impairmentcondition may be applied only to indicate the condition associated witha specific transmission direction e.g. for downlink transmissions suchas the maximum number of DL-SCH transport block bits received in a TTIhas been exceeded or e.g. for uplink transmissions such as the maximumnumber of UL-SCH transport block bits to be transmitted in a TTI hasbeen exceeded.

Specific value in CQI reporting is further discussed herein. In onemethod, upon detection of such an impairment condition or whenreaching/approaching or overshooting a threshold and possibly for acertain amount of time, the WTRU may signal such condition using aspecific CQI value in the signaling for CQI reporting. For example, theWTRU may use the out-of-range (OOR) CQI value. Such indication may betriggered such that it is transmitted using resources of a single CG, orboth CGs.

Indication on PUCCH or in UCI on PUSCH is further discussed herein. Inone method, the WTRU may use one (or more) bit(s) signaled on PUCCH orinside UCI transmitted on PUSCH to indicate the impairment condition.For example, for PUCCH, format 1b (2 bits) may be used such that thesecond bit may report the condition. For example, one bit in PUCCHformat 3 may be reserved for such indication.

Indication using a CSI feedback process is further discussed herein. Inone method, the WTRU may be configured with a dedicated second CSIfeedback process for indicating an impairment condition. For example,the WTRU may use the CSI feedback process to provide overload stateindication/clearance per MAC entity, per CG or even per carrier.

This indication may be extended to a mapping similar to that describedherein for MAC CE signaling.

Indication using Scheduling Request (SR) over PUCCH is further discussedherein. In one method, the WTRU may use a Scheduling Request message toindicate such impairment condition. For example, for PUCCH, format 1b (2bits) may be used such that the second bit may report the condition. Thereinterpretation of the bits contained in the SR message forindication/clearance and other mapping information per eNB/carrier mayalso be possible.

Indication using MAC CE signaling is further discussed herein. In onemethod, the WTRU may use a MAC CE for signaling of such impairmentcondition. For example, the MAC CE may contain a map of the WTRU loadper MAC instance or per CG. Such mapping may be for a single direction(uplink or downlink), or for both. This map may be expressed inpercentages, may express the current load on DL, UL or both and may havea sufficient granularity for eNB to adjust the traffic. This mapping maybe per carrier/direction and may simply indicate which carrier/directionis the most problematic. Such MAC CE may be sent to a single eNB or bothMeNB and SeNB.

Further methods for a condition related to uplink transmissions arefurther discussed herein. In one method, such condition resulting fromuplink transmissions and/or uplink scheduling instructions may bemitigated by using the proposed alternative grant in the uplinkdirection as described herein. The WTRU may use such condition for theselection of an alternative grant using the overload processing or softbits memory depletion as a trigger. In this case, the WTRU may lower thegrant for its uplink transmissions. In some implementations, the WTRUmay perform such alternative grant selection only for a period duringwhich the condition is experienced such as in a period in processingoverload state and/or only for UL overload or power limitation.

The WTRU may use the alternative grant selection method in combinationwith any of the signaling methods described in this document forindicating such condition e.g. the processing overload state.

A trigger for S-RLF with new cause is further discussed herein. In onemethod, the WTRU may avoid failure for an ongoing HARQ process byperforming additional behavior upon detection of such condition. Thismay be useful to avoid a HARQ failure that would be a consequence ofsuch condition such that the WTRU may remain with suitable connectivitytowards the network.

The WTRU may autonomously stop all uplink transmissions for the SCG ifit determines such condition. Additionally, the WTRU may initiate uplinksignaling to indicate the condition using uplink resources of the MCG.Such indication may be according to signaling described above. Suchsignaling may be L3/RRC signaling such as the WTRU failure notificationprocedure. In the latter case, the WTRU may determine that the SCG isexperiencing S-RLF when such condition is detected e.g. once theimpairment state is sustained for a certain amount of time. The WTRU mayreport a new condition such as “WTRU capabilities exceeded” or similar.

For example, the WTRU may start a timer when a certain processing powerpercentage is reached or when a threshold corresponding to one aspect ofits capabilities is exceeded. If this state is sustained over a certainamount of time, the timer will expire and the S-RLF procedure can beinitiated. The WTRU will indicate the condition to the MeNB and it willstop all transmissions using resources associated with the SeNB. In someimplementations, the WTRU may continue performing measurements, as wellas its monitoring of the radio link. It may also maintain its protocolentities and user plane buffer; until MeNB will reconfigure the WTRU(remove the SeNB connection).

Prioritization and Power allocation between MAC instances of differentRATs is further discussed herein. An example embodiment based onguaranteed power and different TTI lengths e.g. for multi-RAT is furtherdiscussed herein. An example wherein a WTRU determines the powerallocation period and related timing of the prioritization function isfurther discussed herein.

In one method, the WTRU may be configured with CGs associated to TTIs ofdifferent duration. For example, the WTRU may be configured with aprimary MAC entity associated to a LTE physical layer (e.g. 1 ms TTI);the WTRU may additionally be configured with a secondary MAC entityassociated to a HSPA physical layer (e.g. 2 ms TTI) or with a secondaryMAC entity associated to a Wifi physical layer. The WTRU may perform anyof the prioritization methods described herein, and in this case applysuch prioritization using a period that corresponds to the longest TTIsacross all configured MAC instances. Alternatively, such period maycorrespond to an integer multiple of the shortest TTI across allconfigured MAC entities which multiple corresponds to the smallestcommon denominator for all configured physical layer. Such period may beconfigured by higher layer (e.g. L3/RRC). The WTRU may determine thestart of such period based on the timing of a specific MAC entity and/orbased on the downlink timing of a specific cell of the WTRU'sconfiguration for that specific MAC entity. Such cell may be a primarycell of the primary MAC entity. Such timing may be the downlink timingfor such cell. Such period may correspond to a configured powerallocation period

Guaranteed power per power allocation period is further discussedherein. The WTRU may be configured with a minimum guaranteed power fordifferent CGs (or MAC instances). Possibly, the WTRU may additionally beconfigured with a power control mode (PCM) or, the WTRU may determinewhat PCM to use based on the type of radio access technology associatedwith the configuration of each MAC entity. The WTRU may apply one ormore prioritization function and/or power allocation function per powerallocation period. The WTRU may apply the configured minimum guaranteedpower per power allocation period. For example, the configuration ofpower allocation periods may include an indication of priority for theconcerned MAC entity for one or more period. For example, for someperiods, a primary MAC entity may have absolute priority over the otherMAC entity. For example, for some periods, the WTRU may instead allocate(or reserve) an amount of power corresponding to the configuredguaranteed power to each MAC entity. Look ahead and schedulinguncertainty for a MAC entity with shortest TTI length is furtherdiscussed herein. The WTRU may determine how to perform power allocationat the start of the power allocation period. The WTRU may have thecapability to determine all required (or possible) uplink transmissionsfor the secondary MAC entity (e.g. the physical layer with the longestTTI length) while it may only have the capability to determine a subsetof the transmissions required for the primary MAC entity (e.g. thephysical layer with the shortest TTI length). In such case, the WTRU mayfirst determine the respective priority associated to the transmissionof each MAC entity (e.g. according to any other method describedherein). If such determination is based on one or more dynamic aspectsand if such dynamic aspect(s) include at least some of the dynamicscheduling information (e.g. at least for the primary MAC entity), theWTRU may determine an amount of power to be assigned to each MACinstance of the power allocation period based on at least thetransmission requirements for (and/or based on the prioritizationfunction applied using) the first TTI of the primary MAC entity. TheWTRU may then apply the same amount to subsequent TTIs of the same powerallocation period. For example, if the WTRU determines from the priorityassociated to each MAC entity that the primary MAC entity shall haveabsolute priority for the entire power allocation period, the WTRU mayuse the total WTRU available power for the transmissions of that MACentity for all TTIs of the power allocation period. For example, if theWTRU determines from the applicable prioritization function that thetotal available power of the WTRU is split to different MAC entitiesaccording to a specific ratio for transmission starting at the beginningof the power allocation period, the WTRU may enforce the same ration forall TTIs of the power allocation period. Such prioritization functionmay be a semi-static split of the total available power.

Power allocation period aligned with DRX/DTX functionality is furtherdiscussed herein. In one example, a period associated with an absolutepriority for a specific MAC instance may correspond (or be aligned with)an inactivity period of the other MAC entity. Such inactivity period maybe based on a DRX algorithm or equivalent. Conversely, a periodassociated with an absolute priority for a specific MAC instance mayinduce an inactivity period for the other MAC entity.

Calculation of total available uplink power for first RAT uses reductiondue to other MAC/RAT entity is further discussed herein. In one example,the WTRU may calculate the total amount of available power for uplinktransmission for transmissions associated to one (or more) MAC entitiesof the same type of radio access technology as a function of the powerallocation in one (or more) MAC entities of a different type of radioaccess technology. For example, for transmissions associated to a LTEMAC entity the WTRU may deduce a certain amount of power allocated tothe other MAC entity (e.g. P_(HSPA) for HSPA or P_(WIFI) for Wifi) andapply such amount as a power reduction when calculating P_(CMAX). Forexample, the configured maximum output power Pome may be set within thefollowing bounds:

P _(CMAX) _(_) _(L,c) ≦P _(CMAX,c) ≦P _(CMAX) _(_) _(H,c)

with

P _(CMAX) _(_) _(L,c)=MIN{P _(EmAx,c) −ΔT _(C,c) ,P_(PowerClass)−MAX(DCPR _(i) +MPR _(c) +A-MPR _(c) +ΔT _(IB,c) +ΔT _(C,c),P-MPR _(c))}P _(CMAX) _(_) _(H,c)=MIN{P _(EMAX,c) ,P _(PowerClass)}

Where DCPR_(i) is the power made available to each MAC entity i that isof a different type of radio access technology than the LTE MACentity(ies) and where other parameters may correspond to 3GPP TS 36.101v12.5.0 (2014-09) section 6.2.5, for example. Possibly, DCPR_(i) mayvary as a function of a prioritization function such as any methoddescribed herein. Possibly, the WTRU may perform such calculation onceper power allocation period.

A permanent hard split is further discussed herein. In another method,the WTRU may be configured with different values for the maximum allowedWTRU output power per MAC entity and/or per MAC entity of the same radioaccess technology e.g. P_(EMAX) or equivalent. Such value may correspondto DCPR_(i) above when calculating available WTRU power for LTE MACentity(ies).

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1. A wireless transmit/receive unit (WTRU) comprising: a processorconfigured to, on a condition that a first uplink transmission for afirst cell group and a second uplink transmission for a second cellgroup are to occur in a same time interval: multiply a maximum transmitpower level by a first proportion for the first cell group to determinea first power level value; allocate a first cell group power level forthe first cell group up to the first determined power level value;multiply the maximum transmit power level by a second proportion for thesecond cell group to determine a second power level value; and allocatea second cell group power level for the second cell group up to aminimum of the second power level value and a remaining power, whereinthe remaining power is a difference between the maximum transmit powerlevel and the first cell group power level; and at least one transmitteroperatively coupled to the processor and configured to transmit thefirst uplink transmission at the first cell group power level and totransmit the second uplink transmission at the second cell group powerlevel.
 2. The WTRU of claim 1, wherein the first cell group comprises afirst radio access technology and the second cell group comprises asecond radio access technology.
 3. The WTRU of claim 2, wherein thefirst radio access technology comprises a long term evolution (LTE)radio access technology.
 4. The WTRU of claim 2, wherein the secondradio access technology comprises a wideband code division multipleaccess radio access technology.
 5. The WTRU of claim 2, wherein thesecond radio access technology comprises a long term evolution (LTE)radio access technology.
 6. The WTRU of claim 2, wherein the secondradio access technology comprises a WiFi radio access technology.
 7. TheWTRU of claim 2, wherein the second radio access technology comprises ahigh speed packet access radio access technology.
 8. A method fortransmitting wireless signals from a wireless transmit/receive unit(WTRU), the method comprising: on a condition that a first uplinktransmission for a first cell group and a second uplink transmission fora second cell group are to occur in a same time interval: multiplying amaximum transmit power level by a first proportion for the first cellgroup to determine a first power level value; allocating a first cellgroup power level for the first cell group up to the first determinedpower level value; multiplying the maximum transmit power level by asecond proportion for the second cell group to determine a second powerlevel value; and allocating a second cell group power level for thesecond cell group up to a minimum of the second power level value and aremaining power, wherein the remaining power is a difference between themaximum transmit power level and the first cell group power level; andtransmitting the first uplink transmission at the first cell group powerlevel and transmitting the second uplink transmission at the second cellgroup power level.
 9. The method of claim 8, wherein the first cellgroup comprises a first radio access technology and the second cellgroup comprises a second radio access technology.
 10. The method ofclaim 9, wherein the first radio access technology comprises a long termevolution (LTE) radio access technology.
 11. The method of claim 9,wherein the second radio access technology comprises a wideband codedivision multiple access radio access technology.
 12. The method ofclaim 9, wherein the second radio access technology comprises a longterm evolution (LTE) radio access technology.
 13. The method of claim 9,wherein the second radio access technology comprises a WiFi radio accesstechnology.
 14. The method of claim 9, wherein the second radio accesstechnology comprises a high speed packet access radio access technology.15. A system for transmitting wireless signals from a wirelesstransmit/receive unit (WTRU) comprising: a first cell group and a secondcell group; a WTRU configured to communicate with the first cell groupand the second cell group, the WTRU comprising a processor and atransmitter; the processor configured to, on a condition that a firstuplink transmission for the first cell group and a second uplinktransmission for the second cell group are to occur in a same timeinterval: multiply a maximum transmit power level by a first proportionfor the first cell group to determine a first power level value;allocate a first cell group power level for the first cell group up tothe first determined power level value; multiply the maximum transmitpower level by a second proportion for the second cell group todetermine a second power level value; and allocate a second cell grouppower level for the second cell group up to a minimum of the secondpower level value and a remaining power, wherein the remaining power isa difference between the maximum transmit power level and the first cellgroup power level; and at least one transmitter operatively coupled tothe processor and configured to transmit the first uplink transmissionat the first cell group power level and to transmit the second uplinktransmission at the second cell group power level.
 16. The system ofclaim 15, wherein the first cell group comprises a first radio accesstechnology and the second cell group comprises a second radio accesstechnology.
 17. The system of claim 16, wherein the first radio accesstechnology comprises a long term evolution (LTE) radio accesstechnology.
 18. The system of claim 16, wherein the second radio accesstechnology comprises a wideband code division multiple access radioaccess technology.
 19. The system of claim 16, wherein the second radioaccess technology comprises a long term evolution (LTE) radio accesstechnology.
 20. The system of claim 16, wherein the second radio accesstechnology comprises a WiFi radio access technology.